System Support ( Hardware, Software and Networking)

Function of a Computer

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A general purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires.
Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits.
The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.

Control unit

Main articles: CPU design and Control unit

Diagram showing how a particular MIPS architecture instruction would be decoded by the control system.

The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into a series of control signals which activate other parts of the computer.^[22] Control systems in advanced computers may change the order of some instructions so as to improve performance.
A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.
The control system's function is as follows—note that this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU:

Read the code for the next instruction from the cell indicated by the program counter.
Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
Increment the program counter so it points to the next instruction.
Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.
Provide the necessary data to an ALU or register.
If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
Write the result from the ALU back to a memory location or to a register or perhaps an output device.
Jump back to step (1).

Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow).
It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program—and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen.

Arithmetic/logic unit (ALU)

The ALU is capable of performing two classes of operations: arithmetic and logic.
The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc.) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?").
Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic.
Superscalar computers may contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.

Memory

Main article: Computer data storage

Magnetic core memory was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory.

A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers.
In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (2^8 = 256); either from 0 to 255 or −128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory.
The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed.
Computer main memory comes in two principal varieties: random-access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary.
In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part.

Input/output (I/O)

Main article: Input/output

Hard disk drives are common storage devices used with computers.

I/O is the means by which a computer exchanges information with the outside world^. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O.
Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics^{[citation needed]}. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.

Multitasking

Main article: Computer multitasking

While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn.
One means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time", then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn.
Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.
Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly — in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.

Multiprocessing

Main article: Multiprocessing

Cray designed many supercomputers that used multiprocessing heavily.

Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed only in large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.
Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers. They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks.

Networking and the Internet

Main articles: Computer networking and Internet

Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved.
In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.

What is Computer

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A computer is a programmable machine that receives input, stores and manipulates data//information, and provides output in a useful format.

While a computer can, in theory, be made out of almost anything (see misconceptions section), and mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). Originally, they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).[1] Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.[2] Simple computers are small enough to fit into mobile devices, and can be powered by a small battery. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers". However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.

Misconceptions

A computer does not need to be electric, nor even have a processor, nor RAM, nor even hard disk. The minimal definition of a computer is anything that transforms information in a purposeful way.

Main article: Unconventional computing

Computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); this is an unintuitive and pedagogical example that a computer can be made out of almost anything. More realistically, modern computers are made out of transistors made of photolithographed semiconductors.

Historically, computers evolved from mechanical computers and eventually from vacuum tube transistors.

There is active research to make computers out of many promising new types of technology, such as optical computing, DNA computers, neural computers, and quantum computers. Some of these can easily tackle problems that modern computers cannot (such as how quantum computers can break some modern encryption algorithms by quantum factoring).
Computer architecture paradigms

Some different paradigms of how to build a computer from the ground-up:

RAM machines

    These are the types of computers with a CPU, computer memory, etc., which understand basic instructions in a machine language. The concept evolved from the Turing machine.
Brains
    Brains are massively parallel processors made of neurons, wired in intricate patterns, that communicate via electricity and neurotransmitter chemicals.
Programming languages
    Such as the lambda calculus, or modern programming languages, are virtual computers built on top of other computers.
Cellular automata
    For example, the game of Life can create "gliders" and "loops" and other constructs that transmit information; this paradigm can be applied to DNA computing, chemical computing, etc.
Groups and committees
    The linking of multiple computers (brains) is itself a computer

Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms.

The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain Turing-complete is, in principle, capable of performing the same tasks that any other computer can perform. Therefore any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity.

Limited-function computers

Conversely, a computer which is limited in function (one that is not "Turing-complete") cannot simulate arbitrary things. For example, a simple four-function calculators cannot simulate a real computer without human intervention. As a more complicated example, without the ability to program a gaming console, it can never accomplish what a programmable calculator from the 1990s could (given enough time); the system as a whole is not Turing-complete, even though it contains a Turing-complete component (the microprocessor). Living organisms (the body, not the brain) are also limited-function computers designed to make a copies of themselves; they cannot be reprogrammed without genetic engineering.

Virtual computers

A "computer" is commonly considered to be a physical device. However, one can create a computer program which describes how to run a different computer, i.e. "simulating a computer in a computer". Not only is this a constructive proof of the Church-Turing thesis, but is also extremely common in all modern computers. For example, some programming languages use something called an interpreter, which is a simulated computer built on top of the basic computer; this allows programmers to write code (computer input) in a different language than the one understood by the base computer (the alternative is to use a compiler). Additionally, virtual machines are simulated computers which virtually replicate a physical computer in software, and are very commonly used by IT. Virtual machines are also a common technique used to create emulators, such game console emulators.

Description About Computer Management

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Event Viewer:

In Windows XP, an event is any significant occurrence in the system or in a program that requires users to be notified, or an entry added to a log. The Event Log Service records application, security, and system events in Event Viewer. With the event logs in Event Viewer, you can obtain information about your hardware, software, and system components, and monitor security events on a local or remote computer. Event logs can help you identify and diagnose the source of current system problems, or help you predict potential system problems.

Event Log Types

A Windows XP-based computer records events in the following three logs:

Application log

The application log contains events logged by programs. For example, a database program may record a file error in the application log. Events that are written to the application log are determined by the developers of the software program.
Security log

The security log records events such as valid and invalid logon attempts, as well as events related to resource use, such as the creating, opening, or deleting of files. For example, when logon auditing is enabled, an event is recorded in the security log each time a user attempts to log on to the computer. You must be logged on as Administrator or as a member of the Administrators group in order to turn on, use, and specify which events are recorded in the security log.
System log

The system log contains events logged by Windows XP system components. For example, if a driver fails to load during startup, an event is recorded in the system log. Windows XP predetermines the events that are logged by system components.

How to View Event Logs

To open Event Viewer, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, click Event Viewer.

The Application, Security, and System logs are displayed in the Event Viewer window.

How to View Event Details

To view the details of an event, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, expand Event Viewer, and then click the log that contains the event that you want to view.
In the details pane, double-click the event that you want to view.

The Event Properties dialog box containing header information and a description of the event is displayed.

To copy the details of the event, click the Copy button, then open a new document in the program in which you want to paste the event (for example, Microsoft Word), and then click Paste on the Edit menu.

To view the description of the previous or next event, click the UP ARROW or DOWN ARROW.

How to Interpret an Event

Each log entry is classified by type, and contains header information, and a description of the event.

Event Header

The event header contains the following information about the event:

Date

The date the event occurred.
Time

The time the event occurred.
User

The user name of the user that was logged on when the event occurred.
Computer

The name of the computer where the event occurred.
Event ID

An event number that identifies the event type. The Event ID can be used by product support representatives to help understand what occurred in the system.
Source

The source of the event. This can be the name of a program, a system component, or an individual component of a large program.
Type

The type of event. This can be one of the following five types: Error, Warning, Information, Success Audit, or Failure Audit.
Category

A classification of the event by the event source. This is primarily used in the security log.

Event Types

The description of each event that is logged depends on the type of event. Each event in a log can be classified into one of the following types:

Information

An event that describes the successful operation of a task, such as an application, driver, or service. For example, an Information event is logged when a network driver loads successfully.
Warning

An event that is not necessarily significant, however, may indicate the possible occurrence of a future problem. For example, a Warning message is logged when disk space starts to run low.
Error

An event that describes a significant problem, such as the failure of a critical task. Error events may involve data loss or loss of functionality. For example, an Error event is logged if a service fails to load during startup.
Success Audit (Security log)

An event that describes the successful completion of an audited security event. For example, a Success Audit event is logged when a user logs on to the computer.
Failure Audit (Security log)

An event that describes an audited security event that did not complete successfully. For example, a Failure Audit may be logged when a user cannot access a network drive.

How to Find Events in a Log

The default view of event logs is to list all its entries. If you want to find a specific event, or view a subset of events, you can either search the log, or you can apply a filter to the log data.

How to Search for a Specific Log Event

To search for a specific log event, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, expand Event Viewer, and then click the log that contains the event that you want to view.
On the View menu, click Find.
Specify the options for the event that you want to view in the Find dialog box, and then click Find Next.

The event that matches your search criteria is highlighted in the details pane. Click Find Next to locate the next occurrence of an event as defined by your search criteria.

How to Filter Log Events

To filter log events, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, expand Event Viewer, and then click the log that contains the event that you want to view.
On the View menu, click Filter.
Click the Filter tab (if it is not already selected).
Specify the filter options that you want, and then click OK.

Only events that match your filter criteria are displayed in the details pane.

To return the view to display all log entries, click Filter on the View menu, and then click Restore Defaults.

How to Manage Log Contents

By default, the initial maximum of size of a log is set to 512 KB, and when this size is reached, new events overwrite older events as needed. Depending on your requirements, you can change these settings, or clear a log of its contents.

How to Set Log Size and Overwrite Options

To specify log size and overwrite options, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, expand Event Viewer, and then right-click the log in which you want to set size and overwrite options.
Under Log size, type the size that you want in the Maximum log size box.
Under When maximum log size is reached, click the overwrite option that you want.
If you want to clear the log contents, click Clear Log.
Click OK.

How to Archive a Log

If you want to save your log data, you can archive event logs in any of the following formats:

Log-file format (.evt)
Text-file format (.txt)
Comma-delimited text-file format (.csv)

To archive a log, follow these steps:

Click Start, and then click Control Panel. Click Performance and Maintenance, then click Administrative Tools, and then double-click Computer Management. Or, open the MMC containing the Event Viewer snap-in.
In the console tree, expand Event Viewer, and then right-click the log in which you want to archive, and then click Save Log File As.
Specify a file name and location where you want to save the file. In the Save as type box, click the format that you want, and then click Save.

The log file is saved in the format that you specified.

Shared Folders

With Windows XP, you can share files and documents with other users on your computer and with other users on a network. There is a new user interface (UI) named Simple File Sharing and a new Shared Documents feature. This article describes the new file sharing UI and discusses the following topics:

How to turn Simple File Sharing on and off.
How to manage and configure levels of access to shares and files.
Guidelines for file sharing in Windows XP.
How to troubleshoot file sharing problems.

Windows XP Home Edition-based computers always have Simple File Sharing enabled.

For information about how to configure file sharing in Windows Vista, visit the following Microsoft Web site:

On a Windows XP-based computer, you can share files among both local and remote users. Local users log on to your computer directly through their own accounts or through a Guest account. Remote users connect to your computer over the network and access the files that are shared on your computer.

You can access the Simple File Sharing UI by viewing a folder's properties. Through the Simple File Sharing UI, you can configure both share and NTFS file system permissions at the folder level. These permissions apply to the folder, all the files in that folder, subfolders, and all the files in the subfolders. Files and folders that are created in or copied to a folder inherit the permissions that are defined for their parent folder. This article describes how to configure access to your files, depending on permission levels. Some information that this article contains about these permission levels is not documented in the operating system files or in the Help file.

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With file sharing in Windows XP, you can configure five levels of permissions. You can configure Levels 1, 2, 4, and 5 by using the Simple File Sharing UI. To do this, right-click the folder, and then click Sharing and Security to open the Simple File Sharing UI. To configure Level 3, copy a file or a folder into the "Shared Documents" folder under "My Computer." This configuration does not change when you turn on or turn off Simple File Sharing. Level 1 is the most private and secure setting, while Level 5 is the most public and the most changeable (nonsecure) setting.

Turning on and turning off Simple File Sharing

Simple File Sharing is always turned on in Windows XP Home Edition-based computers. By default, the Simple File Sharing UI is turned on in Windows XP Professional-based computers that are joined to a workgroup. Windows XP Professional-based computers that are joined to a domain use only the classic file sharing and security interface. When you use the Simple File Sharing UI (that is located in the folder's properties), both share and file permissions are configured.

If you turn off Simple File Sharing, you have more control over the permissions to individual users. However, you must have advanced knowledge of NTFS and share permissions to help keep your folders and files more secure. If you turn off Simple File Sharing, the Shared Documents feature is not turned off.

To turn Simple File Sharing on or off in Windows XP Professional, follow these steps:

Double-click My Computer on the desktop.
On the Tools menu, click Folder Options.
Click the View tab, and then select the Use Simple File Sharing (Recommended) check box to turn on Simple File Sharing. (Clear this check box to turn off this feature.)

To view a video about how to turn Simple File Sharing on or off, click the Play button (

Collapse this imageExpand this image

) on the following Windows Media Player viewer:

Note To view this video, you must have Microsoft Windows Media Player 7.0 or a later version on your computer.

Managing levels of access to shares and to files

You can use Simple File Sharing to configure five levels of access to shares and files:

Level 1: My Documents (Private)
Level 2: My Documents (Default)
Level 3: Files in shared documents available to local users
Level 4: Shared Files on the Network (Readable by Everyone)
Level 5: Shared Files on the Network (Readable and Writable by Everyone)

Notes

By default, files that are stored in "My Documents" are at Level 2.
Levels 1, 2, and 3 folders are available only to a user who is logging on locally. Users who log on locally include a user who logs on to a Windows XP Professional-based computer from a Remote Desktop (RDP) session.
Levels 4 and 5 folders are available to users who log on locally and remote users from the network.

The following table describes the permissions:

Collapse this table Expand this table

Access Level	Everyone (NTFS/File)	Owner	System	Administrators	Everyone (Share)
Level 1	Not available	Full Control	Full Control	Not available	Not available
Level 2	Not available	Full Control	Full Control	Full Control	Not available
Level 3	Read	Full Control	Full Control	Full Control	Not available
Level 4	Read	Full Control	Full Control	Full Control	Read
Level 5	Change	Full Control	Full Control	Full Control	Full Control

Level 1: My Documents (Private)

The owner of the file or folder has read and write permission to the file or folder. Nobody else may read or write to the folder or the files in it. All subfolders that are contained in a folder that is marked as private remain private unless you change the parent folder permissions.

If you are a Computer Administrator and create a user password for your account by using the User Accounts Control Panel tool, you are prompted to make your files and folder private.

Note The option to make a folder private (Level 1) is available only to a user account in its own My Documents folder.

To configure a folder and all the files in it to Level 1, follow these steps:

Right-click the folder, and then click Sharing and Security.
Select the Make this Folder Private check box, and then click OK.

Local NTFS Permissions:

Owner: Full Control
System: Full Control

Network Share Permissions:

Not Shared

Level 2 (Default): My Documents (Default)

The owner of the file or folder and local Computer Administrators have read and write permission to the file or folder. Nobody else may read or write to the folder or the files in it. This is the default setting for all the folders and files in each user's My Documents folder.

To configure a folder and all the files in it to Level 2, follow these steps:

Right-click the folder, and then click Sharing and Security.
Make sure that both the Make this Folder Private and the Share this folder on the network check boxes are cleared, and then click OK.

Local NTFS Permissions:

Owner: Full Control
Administrators: Full Control
System: Full Control

Network Share Permissions:

Not Shared

Level 3: Files in shared documents available to local users

Files are shared with users who log on to the computer locally. Local Computer Administrators can read, write, and delete the files in the Shared Documents folder. Restricted Users can only read the files in the Shared Documents folder. In Windows XP Professional, Power Users may also read, write, or delete any files in the Shared Documents Folder. The Power Users group is available only in Windows XP Professional. Remote users cannot access folders or files at Level 3. To allow remote users to access files, you must share them out on the network (Level 4 or 5).

To configure a file or a folder and all the files in it to Level 3, start Microsoft Windows Explorer, and then copy or move the file or folder to the Shared Documents folder under My Computer.

Local NTFS Permissions:

Owner: Full Control
Administrators: Full Control
Power Users: Change
Restricted Users: Read
System: Full Control

Network Share Permissions:

Not Shared

Level 4: Shared on the Network (Read-Only)

Files are shared for everyone to read on the network. All local users, including the Guest account, can read the files. But they cannot modify the contents. Any user can read and change your files.

To configure a folder and all the files in it to Level 4, follow these steps:

Right-click the folder, and then click Sharing and Security.
Click to select the Share this folder on the network check box
Click to clear the Allow network users to change my files check box, and then click OK.

Local NTFS Permissions:

Owner: Full Control
Administrators: Full Control
System: Full Control
Everyone: Read

Network Share Permissions:

Everyone: Read

Level 5: Shared on the network (Read and Write)

This level is the most available and least secure access level. Any user (local or remote) can read, write, change, or delete a file in a folder shared at this access level. We recommend that this level be used only for a closed network that has a firewall configured. All local users including the Guest account can also read and modify the files.

To configure a folder and all the files in it to Level 5, follow these steps:

Right-click the folder, and then click Sharing and Security
Click to select the Share this folder on the network check box, and then click OK.

Local NTFS Permissions:

Owner: Full Control
Administrators: Full Control
System: Full Control
Everyone: Change

Network Share Permissions:

Everyone: Full Control

Note All NTFS permissions that refer to Everyone include the Guest account.

All the levels that this article describes are mutually exclusive. Private folders (Level 1) cannot be shared unless they are no longer private. Shared folders (Level 4 and 5) cannot be made private until they are unshared.

If you create a folder in the Shared Documents folder (Level 3), share it on the network, and then allow network users to change your files (Level 5), the permissions for Level 5 are effective for the folder, the files in that folder, and the subfolders. The other files and folders in the Shared Documents folder remain configured at Level 3.

Note The only exception is if you have a folder (SampleSubFolder) that is shared at Level 4 inside a folder (SampleFolder) that is shared at Level 5. Remote users have the correct access level to each shared folder. Locally logged-on users have writable (Level 5) permissions to the parent (SampleFolder) and child (SampleSubFolder) folders.

Guidelines

We recommend that you only share folders on the network that remote users on other computers must access. We recommend that you do not share the root of the system drive. When you do this, your computer is more vulnerable to malicious remote users. The Sharing tab of the drive's Properties dialog box contains a warning when you try to share a root folder (for example, C:\). To continue, you must click the If you understand the risk but still want to share the root of the drive, click here link. Only computer administrators can share the root of the drive.

Files on a read-only device such as a CD-ROM shared at Level 4 or 5 are available only if the CD-ROM is in the CD drive. Any CD-ROM that is in the CD drive is available to all users on the network.

A file's permission may differ from the parent folder if one of the following conditions is true:

You use the move command at a command prompt to move a file into the folder from a folder on the same drive that has different permissions.
You use a script to move the file into the folder from a folder on the same drive that has different permissions.
You run Cacls.exe at a command prompt or a script to change file permissions.
Files existed on the hard disk before you installed Windows XP.
You changed a file's permissions while Simple File Sharing was turned off on Windows XP Professional.

Note NTFS permissions are not maintained on file move operations when you use Windows Explorer with Simple File Sharing turned on.

If you turn on and turn off Simple File Sharing, the permissions on files are not changed. The NTFS and share permissions do not change until you change the permissions in the interface. If you set the permissions with Simple File Sharing enabled, only Access Control Entries (ACEs) on files that are used for Simple File Sharing are affected. The following ACEs in the Discretionary Access Control List (DACL) of the files or folders are affected by the Simple File Sharing interface:

Owner
Administrators
Everyone
System

Advanced troubleshooting for configuring file sharing in Windows XP

Note This section is intended for advanced computer users. If you are not comfortable with advanced troubleshooting, ask someone for help or contact support. For information about how to contact support, see the Microsoft Help and Support contact information Web site:

Expected upgrade behavior

A Windows 2000 Professional-based or a Windows NT 4.0-based computer that is joined to a domain or a workgroup that is upgraded to Windows XP Professional maintains its domain or workgroup membership respectively and has the classic file sharing and security UI turned on. NTFS and share permissions are not changed with the upgrade.

By default, if you upgrade a computer that is running Microsoft Windows 98, Windows 98 Second Edition, or Windows Millennium Edition that has "per share" sharing permissions to Windows XP, Simple File Sharing is always turned on. Shares that have passwords assigned to them are removed, and shares that have blank passwords remain shared after the upgrade.

If you upgrade a computer that is running Windows 98, Windows 98 Second Edition, or Windows Millennium Edition to Windows XP Professional and that computer is logged on to a domain, if that computer has share level access turned on and joins the domain while the Setup program is running, the computer starts with Simple File Sharing turned off.

By default, a Windows 98, Windows 98 Second Edition, or Windows Millennium Edition-based computer that is upgraded to Windows XP Home has Simple File Sharing turned on.

Known issues

For remote users to access files from the network (Levels 4 and 5), the Internet Connection Firewall (ICF) must be disabled on the network interface that the remote users connect through.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

When Simple File Sharing is turned on, remote administration and remote registry editing does not work as expected from a remote computer, and connections to administrative shares (such as C$) do not work because all remote users authenticate as Guest. Guest accounts do not have administrative rights. When Simple File Sharing is turned on, if you configure specific user ACEs, remote users are not affected when Simple File Sharing is turned on because all remote users authenticate as Guest when Simple File Sharing is turned on.

Remote users may receive an "Access Denied" message on a share that they had connected to successfully before. This behavior occurs after the hard disk is converted to NTFS. This behavior occurs on Windows XP-based computers that have Simple File Sharing turned on that were upgraded from Windows 98, Windows 98 Second Edition, or Windows Millennium Edition. This behavior occurs because the default permissions of a hard disk that is converted to NTFS do not contain the Everyone group. The Everyone group is required for remote users who are using the Guest account to access the files To reset the permissions, stop sharing, and reshare the affected folders.

Behavior that is affected when Simple File Sharing is turned on

The Simple File Sharing UI in the properties of a folder configures both share and file permissions.
Remote users always authenticate as the Guest account.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:
Windows Explorer does not keep permissions on files that are moved in the same NTFS drive. The permissions are always inherited from the parent folder.
On Windows XP Professional-based computers that have Simple File Sharing turned on and Windows XP Home Edition-based computers, the Shared Folders (Fsmgmt.msc) and Computer Management (Compmgmt.msc) tools reflect a simpler sharing and security UI.
In the Computer Management and Shared Folders consoles, the New File Share command is unavailable when you right-click the Shares icon. Also, if you right-click any listed share, the Properties and Stop Share commands are unavailable.

Behavior that is not caused by turning on Simple File Sharing

In Windows XP Home Edition, the Computer Management snap-in does not display the Local Users and Groups node. The Local Users and Groups snap-in cannot be added to a custom snap-in. This behavior is a limitation of Windows XP Home Edition. It is not caused by Simple File Sharing.
If you turn off the Guest account in the User Accounts Control Panel tool, only the guest's ability to log on locally is affected. The account is not disabled.
Remote users cannot authenticate by using an account that has a blank password. This authentication is configured separately.
Windows XP Home Edition cannot join a domain. It can only be configured as a member of a workgroup.

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Local Users and Groups:

Local Users and Groups is a tool you can use to manage local users and groups. It is available on the following operating systems:

•	Windows 2000 Professional
•	Windows XP Professional
•	Member servers running Windows 2000 Server

A local user or group is an account that can be granted permissions and rights from your computer. Domain or global users and groups are managed by your network administrator. You can add local users, global users, and global groups to local groups. However, you cannot add local users and groups to global groups
Local Users and Groups is an important security feature because you can limit the ability of users and groups to perform certain actions by assigning them rights and permissions. A right authorizes a user to perform certain actions on a computer, such as backing up files and folders or shutting down a computer. A permission is a rule associated with an object (usually a file, folder, or printer) and it regulates which users can have access to the object and in what manner.
Local Users and Groups is not available on domain controllers. Use Active Directory Users and Computers to manage global users and groups.
For more information, see:

•	Working with MMC console files
•	Groups overview
•	Users overview
•	Create a new user account
•	Create a new local group
•	Default security settings

Performance Logs and Alerts:

Performance Logs and Alerts overview

Updated: January 21, 2005
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Performance Logs and Alerts overview

With Performance Logs and Alerts you can collect performance data automatically from local or remote computers. You can view logged counter data using System Monitor or export the data to spreadsheet programs or databases for analysis and report generation. The following list explains the capabilities of Performance Logs and Alerts:

New in the Microsoft® Windows Server 2003 family is the ability to run log collections under different accounts. For example, if you need to log data from a remote computer that requires administrative credentials, you can specify an account with the necessary credentials.
Also new in the Windows Server 2003 family are two new security groups that help you to ensure that only trusted users can access and manipulate sensitive performance data. These are the Performance Log Users group and the Performance Monitor Users group.
The Windows Server 2003 family supports log files greater than 1 GB in size, and with its new log-file format, you can append performance data to an existing log file.
Performance Logs and Alerts collects data in a comma-separated or tab-separated format for easy import to spreadsheet programs. A binary log-file format is also provided for circular logging or for logging instances such as threads or processes that may begin after the log starts collecting data. (Circular logging is the process of continuously logging data to a single file, overwriting previous data with new data.)
You can also collect data in an SQL database format. This option defines the name of an existing SQL database and log set within the database where the performance data will be read or written. This file format is useful when collecting and analyzing performance data at an enterprise level rather than on a per-computer basis. Logging data directly to a SQL database is supported through open database connectivity (ODBC).
Counter data collected by Performance Logs and Alerts can be viewed during collection as well as after collection has stopped.
Because logging runs as a service, data collection occurs regardless of whether any user is logged on to the computer being monitored.
You can define start and stop times, file names, file sizes, and other parameters for automatic log generation.
You can manage multiple logging sessions from a single console window.
You can set an alert on a counter, thereby defining that a message be sent, a program be run, an entry made to the application event log, or a log be started when the selected counter's value exceeds or falls below a specified setting.

Similar to System Monitor, Performance Logs and Alerts supports defining performance objects, performance counters, and performance object instances. It also supports setting sampling intervals for monitoring data about hardware resources and system services. Performance Logs and Alerts also offers other options related to recording performance data:

Start and stop logging either manually on demand or automatically based on a user-defined schedule.
Configure additional settings for automatic logging, such as automatic file renaming, and set parameters for stopping and starting a log file based on the elapsed time or the file size.
Create trace logs. Using the default Windows Server 2003 family data provider or another application provider, trace logs record detailed system application events when certain activities, such as a disk I/O operation or a page fault, occurs. When the event occurs, your operating system logs the system data to a file specified by the Performance Logs and Alerts service. This differs from the operation of counter logs; when counter logs are in use, the service obtains data from the system when the update interval has elapsed, rather than waiting for a specific event. A parsing tool is required to interpret the trace log output. Developers can create such a tool using application programming interfaces (APIs) provided in the MSDN Library on the Microsoft Web site.
You can also produce trace analysis reports from trace log output files using the Tracerpt tool. Use this tool to process kernel, Active Directory, and other transactional based trace event logs, and to generate trace analysis reports and .csv files from binary logs.
Define a program that runs when a log is stopped.
If you want to export log data to Microsoft Excel, the Performance Logs and Alerts service must be stopped because Microsoft Excel requires exclusive access to the log file. Most other programs are not known to require this exclusive access; therefore, in general you can work with data from a log file while the service is collecting data to that file.

Device Manager

Screenshot of the Device Manager tool under Windows Vista.

Screenshot of the Device Manager tool under Windows Server 2003 showing hardware components organized under categories.

The Device Manager is a Control Panel applet in Microsoft Windows operating systems. It allows users to view and control the hardware attached to the computer. When a piece of hardware is not working, the offending hardware is highlighted for the user to deal with. The list of hardware can be sorted by various criteria.
For each device, users can:

Supply device drivers for the hardware
Enable or disable devices
Tell Windows to ignore malfunctioning devices
View other technical properties

Device Manager was introduced with Windows 95 and later added to Windows 2000 by Ruben Ashimbanga. In NT-based versions, it is included as a Microsoft Management Console snap-in.

Storage types and partition styles

Windows XP Professional and offer two types of disk storage: basic disk and dynamic disk.

Basic disks

A basic disk is a physical disk that contains primary partitions, extended partitions, or logical drives. You can perform the following tasks only on a basic disk:

•	Create and delete primary and extended partitions
•	Create and delete logical drives within an extended partition.
•	Format a partition and mark it as active
•	Check disk properties, such as capacity, available free space, and current status.
•	View volume and partition properties such as size, drive letter assignment, label, type, and file system.
•	Establish drive letter assignments for volumes or partitions, optical storage devices (for example CD-ROM), and removable drives.
•	Establish disk sharing and security arrangements for volumes and partitions formatted with NTFS.
•	Convert a basic disk to dynamic.

For more information about converting a disk from basic to dynamic, see Converting a basic disk to dynamic
For more information about basic disks and volumes, see Basic disks and volumes

Dynamic disks

Dynamic disks provide features that basic disks do not, such as the ability to create volumes that span multiple disks (spanned and striped volumes), and the ability to create fault-tolerant volumes (mirrored and RAID-5 volumes). All volumes on dynamic disks are known as dynamic volumes. You can perform the following tasks only on a dynamic disk:

•	Create and delete simple, spanned, striped, mirrored, and RAID-5 volumes.
•	Extend a simple or spanned volume.
•	Remove a mirror from a mirrored volume or split the volume into two volumes.
•	Repair mirrored or RAID-5 volumes.
•	Reactivate a missing or offline disk.
•	Check disk properties, such as capacity, available free space, and current status.
•	View volume and partition properties such as size, drive letter assignment, label, type, and file system.
•	Establish drive letter assignments for volumes or partitions, optical storage devices (for example CD-ROM), and removable drives.
•	Establish disk sharing and security arrangements for volumes and partitions formatted with NTFS.
•	Change a dynamic disk to basic.

For more information about dynamic disks and volumes, see Dynamic disks and volumes

Partition styles

Partition style refers to the method that Windows XP and use to organize partitions on the disk. All x86-based computers use the partition style known as master boot record (MBR) MBR contains a partition table that describes where the partitions are located on the disk. Because MBR is the only partition style available on x86-based computers, you do not need to choose this style; it is used automatically.
Itanium-based computers running Windows XP 64-Bit Edition, Whistler Advanced Server for Intel Itanium systems, or Whistler Datacenter Server for Intel Itanium systems use a new partition style called GUID partition table (GPT) There are some differences between GPT and MBR partition styles, but most disk-related tasks are unchanged. Basic disks and dynamic disks work the same way as in Windows 2000, and these storage types are available on disks that use either partition style. For more information about GPT disks, see GUID partition table (GPT)
Computers running Windows XP 64-Bit Edition, Whistler Advanced Server for Intel Itanium systems, or Whistler Datacenter Server for Intel Itanium systems require a GPT disk that contains an Extensible Firmware Interface (EFI) System partition and the files necessary to start the computer. You can also install MBR disks on Itanium-based systems, but you cannot start a system from them. For more information about EFI and EFI System partitions, see Extensible Firmware Interface
In order to more easily differentiate between disks that use the MBR and GPT partition styles, Disk Management labels disks that use the master boot record partition style as MBR disks, while disks that use the GUID partition table partition style are labeled GPT disks.
The following table depicts storage types and partition styles in Windows XP and :

Operating system	Storage types	Partition styles
Basic volumes	Dynamic simple, spanned, and stripped volumes	Dynamic mirrored and RAID-5 volumes
Windows XP Home Edition	X
Windows XP Professional	X	X
Whistler	X	X
Whistler Advanced Server	X	X
Whistler Server	X	X
Windows XP 64-Bit Edition	X	X
Whistler Advanced Server for Intel Itanium systems	X	X
Whistler Datacenter Server for Intel Itanium systems	X	X

Removable Storage
The data storage and management features in the Windows Server 2003 operating system provide you with various ways to manage and store data. With Removable Storage, a primary component of this feature set, you can track your removable storage media (tapes and optical disks) and manage the hardware libraries, such as changers and jukeboxes, which contain them.
With Removable Storage, you can:

Label, catalog, and track media.
Control library drives, slots, and doors.
Perform drive-cleaning operations.

Removable Storage works together with your data-management applications such as Backup. You use data-management applications to manage the actual data stored on the media. Removable Storage makes it possible for multiple applications to share the same storage media resources, which can reduce your costs. It also provides a common interface for managing those resources, so that you can manage your storage media more efficiently.
Removable Storage organizes all the media in your libraries into different media pools. A media pool is a logical collection of removable media that have the same management policies. Media pools are used by applications to control access to specific tapes or discs within libraries that are managed by Removable Storage. Removable Storage also moves media between media pools in order to provide the amount of data storage that your applications require
You cannot use Removable Storage to manage volumes, such as for media siding or striping. Also, you cannot use Removable Storage to manage files, such as for data backup or disk-extender operations. These services are performed by data-management applications such as Backup or Remote Storage. Remote Storage is not available on computers running Windows XP Professional; Windows Server 2003, Web Edition; or Windows Server 2003, Standard Edition.
You must run all your data-management applications on the same computer that connects to your library. Removable Storage does not support multiple data-management applications running on different computers that are connected to the same library.
Removable Storage is configured to start automatically when you start your computer. It is possible to change the service so that you can start it manually, but this is highly discouraged. Disabling the service causes several applications that are included in Windows Server 2003 (such as Backup and Remote Storage) to become inoperative.

Common Scenarios for Removable Storage

Removable Storage is commonly used in the following scenarios:

Managing stand-alone drive libraries
Managing automated libraries

Managing stand-alone drive libraries

In this scenario, you use Removable Storage to manage multiple single-drive libraries, such as CD-ROM or DVD-ROM drives.
In its simplest form, a library consists of data-storage media and the device that is used to read from and write to the media – for example, tape and a stand-alone tape drive. The group of libraries and associated media that you manage with a Removable Storage installation is called a Removable Storage system.
The main benefit to using Removable Storage is its efficiency: it is much easier to manage multiple libraries with a single tool, the Removable Management MMC snap-in, on behalf of different data-management applications, than it is to individually manage the same libraries with different sets of tools from those applications.
A further benefit of Removable Storage is that it organizes all the media in your libraries into different media pools, and also moves media between media pools in order to provide the appropriate amount of data storage your applications require.

Managing automated libraries

In this scenario, you use Removable Storage to manage one or more automated libraries.
Automated libraries are automated units that hold multiple tapes or disks, and some have multiple drives. These libraries are sometimes called changers or jukeboxes, and commonly use robotic subsystems to move media stored in the library’s storage slots.
You can also use Removable Storage to manage a combination of single-drive and automated libraries.
The benefits are the same as the ones described in the previous scenario.

Administrative Interface

The Removable Storage Microsoft Management Console (MMC) snap-in is an administrative interface that you can use to manage both stand-alone drive libraries and automated libraries.
Using the Removable Storage snap-in, you can:

Create media pools and set media pool properties.
Insert and eject media in an automated library.
Mount and dismount media.
Clean tape drives.
View the state of media and libraries.
Enable and disable drives and libraries.
Perform library inventories
Set security permissions for users.
Complete or refuse operator requests
Cancel work queue items.

Removable Storage Dependencies on or Interactions with Other Technologies

Removable Storage depends on, or interacts with, the following technologies:

Microsoft Management Console (MMC)
Backup (or similar, non-Microsoft data-management programs)
Win32 tape and disk management application programming interfaces (APIs)
The registry
Event Viewer
Group Policy
Media libraries

Removable Storage Logical Diagram

The first part of the following figure shows the inherent complexity in using multiple applications to manage multiple devices (each containing a different media-type) without the aid of Removable Storage.
The second part shows how you can reduce this complexity by using Removable Storage as the common interface for managing multiple devices.
Removable Storage Logical Diagram

This article describes how to assign, to change, or to remove drive letters on a drive, a partition, or a volume by using the Disk Management snap-in in Microsoft Windows XP.

The Disk Management snap-in is an administrative tool for managing hard disks and the volumes or partitions that they contain. Use the Disk Management snap-in when you want to add, to change, or to remove drive letters on drives, on partitions, or on volumes on your computer's hard disks, CD-ROM drives, and other removable media devices.

Your computer can use up to 26 drive letters, from A through Z. Use drive letters C through Z for hard disk drives. Drive letters A and B are reserved for floppy disk drives. However, if your computer does not have a floppy disk drive, you can assign these letters to removable drives.

Before you modify drive-letter assignments, note the following items:

Changing the drive letter of the system volume or the boot volume is not a built-in feature of the Disk Management snap-in.
Many MS-DOS-based and Microsoft Windows-based programs refer to specific drive letters for environmental or other variables. If you modify the drive letter, these programs may not function correctly.

How to assign a drive letter

To assign a drive letter to a drive, a partition, or a volume, follow these steps:

Log on as Administrator or as a member of the Administrators group.
Click Start, click Control Panel, and then click Performance and Maintenance.

Note If you do not see Performance and Maintenance, go to step 3. Performance and Maintenance appears in Control Panel only if you use Category view. If you use Classic view, Performance and Maintenance does not appear.
Click Administrative Tools, double-click Computer Management, and then click Disk Management in the left pane.
Right-click the drive, the partition, the logical drive, or the volume that you want to assign a drive letter to, and then click Change Drive Letter and Paths.
Click Add.
Click Assign the following drive letter if it is not already selected, and then either accept the default drive letter or click the drive letter that you want to use.
Click OK.

The drive letter is assigned to the drive, to the partition, or to the volume that you specified, and then that drive letter appears in the appropriate drive, partition, or volume in the Disk Management tool.

How to change a drive letter

To change an existing drive letter on a drive, on a partition, or on a volume, follow these steps:

Log on as Administrator or as a member of the Administrators group.
Click Start, click Control Panel, and then click Performance and Maintenance.
Click Administrative Tools, double-click Computer Management, and then click Disk Management in the left pane.
Right-click the drive, the partition, the logical drive, or the volume that you want to assign a drive letter to, and then click Change Drive Letter and Paths.
Click Change.
Click Assign the following drive letter if it is not already selected, click the drive letter that you want to use, and then click OK.
Click Yes when you are prompted to confirm the drive letter change.

The drive letter of the drive, the partition, or the volume that you specified is changed, and the new drive letter appears in the appropriate drive, partition, or volume in the Disk Management tool.

How to remove a drive letter

To remove an existing drive letter on a drive, on a partition, or on a volume, follow these steps:

Log on as Administrator or as a member of the Administrators group.
Click Start, click Control Panel, and then click Performance and Maintenance.
Click Administrative Tools, double-click Computer Management, and then click Disk Management in the left pane.
Right-click the drive, the partition, the logical drive, or the volume that you want to assign a drive letter to, and then click Change Drive Letter and Paths.
Click Remove.
Click Yes when you are prompted to confirm the removal.

The drive letter is removed from the drive, from the partition, or from the volume that you specified.

Troubleshooting

When you try to change an existing drive letter, you receive the following error message:

The volume volume_label drive_letter is currently in use.
If you continue, the new drive letter will be assigned; but you can still use the old drive letter to access the volume until you restart your computer. The old drive letter will not be available for assignment until you restart.

Warning: Changing the drive letter of a volume could cause programs to no longer run.

This error message may appear if there are files that are in use on the drive, on the partition, or on the volume. These files may be in use by you or by other people on the network. To resolve this issue, use one of the following methods:

Click No when you receive the error message. Quit all the programs that are using the files on the volume, and then change the drive letter. To do this, right-click the volume, click Change Drive Letter and Paths, and then click Change.
Click Yes to continue with the drive letter change.

When you try to remove an existing drive letter, you receive the following error message:

The volume volume_label drive_letter is currently in use.
If you continue, the drive letter will be freed; however, it will still be available for use until you restart your computer.

Warning: Changing the drive letter of a volume could cause programs to no longer run.

This error message may appear if there are files that are in use on the drive, the partition, or the volume. These files may be in use by you or by other people on the network. To resolve this issue, use one of the following methods:

Click No when you receive the error message. Quit all the programs that are using the files on the volume, and then remove the drive letter. To do this, right-click the volume, click Change Drive Letter and Paths, and then click Remove.
Click Yes to remove the drive letter the next time that you start your computer.

Disk Defragmenter

Disk Defragmenter A component of Microsoft Windows

Disk Defragmenter in Windows 7
Details

Disk Defragmenter is a computer program included in Microsoft Windows designed to increase access speed by rearranging files stored on a disk to occupy contiguous storage locations, a technique commonly known as decrementing. The purpose is to optimize the time it takes to read and write files to/from the disk by minimizing head travel time and maximizing the transfer rate. As of Windows XP, Disk Defragmenter is also used to improve system startup times.

Disk Management:

This step-by-step article describes how to use the Windows XP Disk Management snap-in to configure a basic disk and prepare it for use. This article also describes how to create and delete partitions, and how to format volumes with the FAT, FAT32, or NTFS file systems.

MORE INFORMATION

Basic disks and volumes Basic disk storage supports partition-oriented disks. A...

Basic disks and volumes

Basic disk storage supports partition-oriented disks. A basic disk is a physical disk that contains primary partitions, extended partitions, or logical drives. Partitions and logical drives on basic disks are also known as basic volumes. You can create up to four primary partitions, or three primary partitions and one extended partition, that contain logical drives.

If you are running Windows XP Professional and one or more of the following operating systems on the same computer, you must use basic volumes, because these operating systems cannot access data that is stored on dynamic volumes:

Windows XP Home Edition
Microsoft Windows NT 4.0 or earlier
Microsoft Windows Millennium Edition (Me)
Microsoft Windows 98
Microsoft Windows 95
MS-DOS

How to use Disk Management

To start Disk Management:

Log on as administrator or as a member of the Administrators group.
Click Start, click Run, type compmgmt.msc, and then click OK.
In the console tree, click Disk Management. The Disk Management window appears. Your disks and volumes appear in a graphical view and list view. To customize how you view your disks and volumes in the upper and lower panes of the window, point to Top or Bottom on the View menu, and then click the view that you want to use.

NOTE: Microsoft recommends that you create a full back up of your disk contents before you make any changes to your disks or volumes.

How to create a new partition or a new logical drive

To create a new partition or logical drive on a basic disk:

In the Disk Management window, complete one of the following procedures, and then continue to step 2:

To create a new partition, right-click unallocated space on the basic disk where you want to create the partition, and then click New Partition.
To create a new logical drive in an extended partition, right-click free space on an extended partition where you want to create the logical drive, and then click New Logical Drive.

In the New Partition Wizard, click Next.
Click the type of partition that you want to create (either Primary partition, Extended partition, or Logical drive), and then click Next.
Specify the size of the partition in the Partition size in MB box, and then click Next.
Decide whether to manually assign a drive letter, let the system automatically enumerate the drive, or do not assign a drive letter to the new partition or logical drive, and then click Next.
Specify the formatting options you want to use by using one of the following procedures:

If you do not want to format the partition, click Do not format this partition, and then click Next.
If you want to format the partition, click Format this partition with the following settings, and then complete the following procedure in the Format dialog box:

a. Type a name for the volume in the Volume label box. This is an optional step.

b. Click the file system that you want to use in the File system box.

You can change the disk allocation unit size, and then specify whether to perform a quick format, or enable file and folder compression on NTFS volumes.

Click Next.

Confirm that the options that selected are correct, and then click Finish.

The new partition or logical drive is created and appears in the appropriate basic disk in the Disk Management window. If you chose to format the volume in step 6, the format process now starts.

How to format a basic volume

To format a partition, logical drive or basic volume:

In the Disk Management window, right-click the partition or logical drive that you want to format (or reformat), and then click Format.
In the Format dialog box, type a name for the volume in the Volume label box. This is an optional step.
Click the file system that you want to use in the File system box. If you want, you can also change the disk allocation unit size, specify whether you want to perform a quick format, or enable file and folder compression on NTFS volumes.
Click OK.
Click OK when you are prompted to format the volume. The format process starts.

How to view the properties of a basic volume

To view the properties of a partition or logical drive:

In the Disk Management window, right-click the partition or logical drive that you want, and then click Properties.
Click the appropriate tab to view the appropriate property.

How to delete a partition or a logical drive

To delete a partition or logical drive:

In the Disk Management window, right-click the partition or logical drive that you want to delete, and then click Delete Partition or Delete Logical Drive.
Click Yes when you are prompted to delete the partition or logical drive. The partition or logical drive is deleted.

Important

When you delete a partition or a logical drive, all the data on that partition or logical drive, and the partition or the logical drive, are deleted.
You cannot delete the system partition, boot partition, or a partition that contains the active paging (swap) file.
You cannot delete an extended partition unless the extended partition is empty. All logical drives in the extended partition must be deleted before you can delete the extended partition.

Troubleshooting

Disk Management displays status descriptions in graphical view and under the Status column of list view to inform you of the current status of the disk or volume. Use these status descriptions to help you detect and troubleshoot disk and volume failures. The following is a partial list of disk and volume status descriptions:

Online
This is the normal disk status when the disk is accessible and functioning correctly.
Healthy
This is the normal volume status when the volume is accessible and functioning correctly.
Unreadable
The disk is inaccessible because of possible hardware failure, corruption, or I/O errors.

To troubleshoot this issue, restart the computer or rescan the disk to try and return the disk to Online status. To rescan the disk, open Computer Management, and then click Disk Management. On the Action menu, click Rescan Disks.

For a complete list of disk and volume status descriptions and troubleshooting procedures, see Disk Management Help. In the Disk Management snap-in or Computer Management window, click Help on the Action menu.

Services :

list of all the standard services [update: SP 2 defaults are shown in Green]

ServiceName	Service (Key)	Process	Description	Default Status & notes
Alerter	Alerter	Services.exe [HKLM\SYSTEM\ CurrentControlSet\ Services\Alerter\Parameters] [HKLM\SYSTEM\ CurrentControlSet \Services\SysmonLog\Log Queries\<alertname>]	Distribute administrative alerts to specific users or machines. e.g. Performance Monitor thresholds are distributed as alerts. Requires the Messenger and Workstation services to be started.	Manual. May be disabled if the alerts are not needed.
Application Layer Gateway Service	ALG	alg.exe	Support for Internet Connection Sharing and the Internet Connection Firewall	Manual
Application Management	appmgt	Services.exe or svchost.exe	Installation services (Add/Remove Programs) - Assign, Publish, and Remove.	Manual
Automatic Updates	wuaUserv	svchost.exe -k wugroup	Enable the download and installation of critical Windows updates.	Automatic. If the service is stopped, the operating system can be manually updated at the Windows Update Web site.
Background Intelligent Transfer Service	BITS	svchost.exe -k BITSgroup	Transfer files using idle network bandwidth, maintain file transfers through network disconnections and computer restarts.	Automatic switch to manual if you have problems - Q314862
Clipbook Server	Clipsrv	Clipsrv.exe	Provides support for the Clipbook Viewer, which allows the clipboard of the source machine to be accessed remotely.	Disabled
COM+ Event System	Event System	svchost.exe -k netsvcs	Automatic distribution of events to subscribing COM components.	Manual
Computer Browser	Browser	Services.exe	Collects the names of NetBIOS resources on the network, creating a list so that it can participate as a master browser or basic browser (one that takes part in browser elections). This maintained list of resources (computers) is displayed in Network Neighborhood and Server Manager. If disabled you can still map drives, but can't browse the whole network.	Automatic. If the machine is not connected to a LAN (stand-alone), or will not participate as a master browser or take part in elections, then feel free to change the status to manual (or disabled) This does not equate to disabling TCP/IP so internet browsing is still possible.
Cryptographic Services	CryptSvc	svchost.exe	Management of Certification Authority certificates. Driver Catalog Database, Protected Root and Key certificate Services.	Automatic
DCOM Server Process Launcher	DcomLaunch	svchost.exe	Launch DCOM services	Automatic
DHCP Client	Dhcp	Services.exe or svchost.exe	Manage network configuration by registering and updating IP addresses and DNS names.	Automatic On a stand-alone machine: Disable
Distributed Link Tracking Client	TrkWks	Services.exe or svchost.exe	Send notification of files moving between NTFS volumes in a network domain.	Automatic Can be set to manual if you dont need this function.
Distributed Transaction Coordinator	msdtc	MSDTC.exe	Coordinate transactions that are distributed across two or more databases, message queues, file systems, or other transaction protected resource managers.	Manual Can be set to Disabled if you dont need this function.
DNS Client	Dnscache	Services.exe	Resolves and caches Domain Name System (DNS) names.	Automatic
Directory Replicator (Server only)	Replicator	Lmrepl.exe	Replicate specified files & folders between computers. The host is the export server, and the target machines are called import computers. Replication is configured under Server in the Control Panel.	Automatic Domain Controllers need this to replicate the Netlogon share.
Error Reporting Service	Ersvc	svchost.exe	Report errors back to Microsoft in Redmond.	Automatic If you never want to report system crash info. to Microsoft set this to disabled.
EventLog	EventLog	Services.exe	Record System, Security, and Application Events. Viewed with the MMC Event Viewer (eventvwr.exe in NT).	Automatic
Fast User Switching Compatibility	FastUserSwitching Compatibility	svchost.exe	Enable multiple users to login to the same PC simultaneously.	Manual
Fax Service	Fax	faxsvc.exe	Send and receive faxes	Automatic or Manual
Help and Support	helpsvc	svchost.exe	Help and Support Center	Automatic. If stopped the help system will stop working.
Human Interface Device Access	HidServ	svchost.exe	Support for extra keyboard 'hot buttons' and other multimedia input devices.	Disabled
HTTP SSL	HTTPFilter	svchost.exe	Support for HTTPS (Secure Socket Layer) websites such as banking and e-commerce.	Manual
IMAPI CD-Burning COM Service	ImapiService	imapi.exe	CD-Rom Burning	Manual If you have problems changing to Automatic may help.
Indexing Service	cisvc	cisvc.exe	Index the contents and properties of files on local and remote computers. [ RESOURCE HOG ]	Manual For improved performance Disable or Uninstall thru C.Panel add/remove
IPSEC Policy Agent	PolicyAgent	lsass.exe	Manage IP security policy and starts the ISAKMP/Oakley (IKE) and the IP security driver.	Automatic May be changed to Manual if IPSec is not needed.
License Logging Service (Server)	LicenseService	Llssrv.exe	License tracking on a server or DC (Domain Controller).	If disabled then licensing status alerts will not be generated.
Logical Disk Manager	Dmserver	services.exe or svchost.exe	Required by the MMC Disk Management plug-in.	Automatic
Logical Disk Manager Administrative Service	Dmadmin	dmadmin.exe /com	Administrative service for disk management requests	Manual
Message Queuing		mqsvc.exe	Message Queuing
Message Queuing Triggers		mqtgsvc.exe	Message Queuing
MS Software Shadow Copy Provider Service	swprv	dllhost.exe	Microsoft Backup Utility	Manual Disable if you never use Shadow Copy features.
Messenger	Messenger	Services.exe	Process the receipt or delivery of pop-up messages sent via NET SEND. Not related to Windows Messenger	Disabled vulnerability once used to send pop-up spam.
Network Connections	Netman	svchost.exe -k netsvcs	Manage objects in the Network and Dial-Up Connections folder (LAN and remote connections.)	Manual
Net Logon	Netlogon	Lsass.exe (Local Security Authority Subsystem)	Network Authentication: maintains a synced domain directory database between the PDC and BDC(s), handles authentication of respective accounts on the DCs, and authenticates domain accounts on networked machines.	Automatic For stand-alone machines never connected to a domain set to Manual.
NetMeeting Remote Desktop Sharing	Nmnsrvc	mnmsrvc.exe	Allows authorized people to remotely access your Windows desktop using NetMeeting.	Manual. A good idea to Disable unless you plan to allow remote connections.
Network DDE	NetDDE	Netdde.exe	Support the network transport of DDE (Dynamic Data Exchange) connections. Requires Network DDE DSDM to be started. See Clipbook service	Disabled
Network DDE DSDM	NetDDEdsdm	Netdde.exe	Manage shared DDE conversations (from shares like: \\computername\ndde$). See Clipbook service	Disabled
NLA - Network Location Awareness	nla	svchost.exe	Part of Internet Connection Sharing (ICS) and the Internet Connection Firewall (ICF)	Manual
Network Provisioning Service	xmlprov	svchost.exe	Manage XML configuration files on a domain basis	Manual
NT LM Security Support Provider	NtLmSsp	Services.exe	Extends NT security to Remote Procedure Call (RPC) programs using various transports other than named pipes. RPC activity is quite common, and most RPC apps don't use named pipes.	Manual
Performance Logs and Alerts (XP) Alerts and Performance Logs (Win 2K)	sysmonLog	smlogsvc.exe	Configure performance logs and alerts.	Manual. May be disabled if the alerts are not needed.
Plug and Play	PlugPlay	Services.exe	Plug and Play. Do not disable this service.	Automatic
Universal Plug and Play Host	UPNPhost	svchost.exe	Device Host detect and configure external UPnP devices. UPnP<>PnP	Manual
Portable Media Serial Number Service	WmdmPmSN	svchost.exe	Retrieves the serial number of any portable media player connected to this computer.	Manual Disable if you never use DRM music devices.
Print Spooler or Spooler	Spooler	Spoolsv.exe (Spoolss.exe in NT4)	The NT printing subsystem.	Automatic - If you print documents. If no printing is ever done set to manual (or disabled) Restarting this service will cancel all pending print jobs.
Protected Storage	ProtectedStorage	Pstores.exe	Encrypt and store secure info: SSL certificates, passwords for Outlook, Outlook Express, Profile Assistant, MS Wallet, and digitally signed S/MIME keys.	Automatic.
QoS RSVP	rsvp	rsvp.exe -s	Provide network signaling and local traffic control setup functionality for QoS-aware programs and control applets.	Manual
Remote Access Auto Connection Manager or Remote Access AutoDial Manager	Rasauto	svchost.exe -k netsvcs	Activates automatic dial-up when a URL link is clicked. Required for some but not all RAS, ADSL or Cable connections.	Manual May be disabled if the machine has no internet access.
Remote Access Connection Manager	Rasman	svchost.exe -k netsvcs	Required for most but not all RAS, ADSL or Cable connections.	Manual. Required for Internet Connection Sharing or accessing remote servers via RAS.
Remote Desktop Help Session Manager	RDSessMgr	sessmgr.exe	Remote Desktop Help Session Manager.	Manual May be disabled if RDP is never used.
Remote Procedure Call (RPC) Service or Remote Procedure Call (RPC)	RpcSs	svchost -k rpcss	This RPC subsystem is crucial to the operations of any RPC activities taking place on a system (e.g. DCOM)	Automatic Do not disable Many essential services are dependent on RPC.
Remote Procedure Call (RPC) Locator	RpcLocator	Locator.exe	Maintain the RPC name server database, requires the RPC service (below) to be started. Database of available server applications.	Manual.
Remote Registry Service (XP Pro only)	RemoteRegistry	regsvc.exe	Allow remote registry manipulation.	Automatic A good idea to disable this, unless you have some reason to allow remote registry editing.
Removable Storage	Ntmssvc	svchost.exe -k netsvcs	Manage removable media, drives, and libraries.	Manual.
RIP Listener (XP - option)			Listen for RIP announcements from routers and modify the routing table accordingly.	To use the RIP Listener service, your adjacent routers must support the RIP v1 protocol. You'll find the RIP Listener service under Add/Remove Windows Components - Networking Services.
Routing and Remote Access	RemoteAccess	svchost.exe -k netsvcs	Allow incoming connections via dial in or VPN. (WAN Routing)	Disabled
Secondary Logon (Win XP) RunAs (Win 2K)	secLogon	services.exe or svchost.exe	Enables starting processes under alternate credentials.	Automatic You may want to stop this service if you never use RunAs
Security Accounts Manager (Win 2K)	SamSs	lsass.exe	Stores security information for local user accounts.	Automatic
Security Center	wscsvc	svchost.exe	Monitor system security settings and configurations.	Automatic You may want to disable this if firewall and virus updates are controlled via other means.
Server	LanmanServer	Services.exe	Support for peer-to peer file sharing, print sharing, and named pipe sharing via SMB services.	Automatic May be disabled if you dont host file or print shares. (Admin$ shares)
Shell Hardware Detection	ShellHWDetection	svchost.exe	CD Autoplay	Automatic.
Smart Card	ScardSrv	SCardSvr.exe	Manages and controls access to a smart card inserted into a smart card reader attached to the computer.	Manual If you never use smart cards, Disable
Smart Card Helper	ScardDrv	SCardSvr.exe	legacy smart card readers	Removed in XP SP2
SNMP Service	Snmp	snmp.exe	Agents that monitor the activity in network devices and report to the network console workstation.	Automatic (if installed)
SSDP Discovery Service	SSDPSRV	svchost.exe	Simple Service Discovery Protocol. Enables discovery of UPnP devices on your home network	Manual May be disabled if as is likely you dont have any UPnP devices)
System Event Notification	SENS	svchost.exe -k netsvcs	Track system events such as Windows logon, network, and power events. Notifiy COM+ Event System subscribers of these events.	Automatic.
System Restore Service	srservice	svchost.exe	Creates system snap shots. [ RESOURCE HOG ]	Automatic If the machine's configuration has been cloned/backed up - turn off System Restore in Control Panel, System.
Task Scheduler or Schedule	Schedule	atsvc.exe or mstask.exe	This service is required to schedule background tasks (run at a specific date & time) Under NT it's a Resource Hog. Under XP it's used by some auto-tuning operations.	Automatic
TCP/IP NetBIOS Helper or TCP/IP NetBIOS Helper Service	lmHosts	Services.exe	Support for name resolution in a Windows 2000 domain. (Netbios/Wins) An alternative to DNS lookup.	Automatic If not required may be set to manual.
Telephony	TapiSrv	Tapisrv.exe	Telephony API (TAPI) support for programs that control telephony devices and IP based voice connections. e.g unimodem modems.	Manual
Telnet (Win 2K)	TlntSvr	tlntsvr.exe	Allows a remote user to log on to the system and run console programs using the command line.	Disabled Very insecure, presents a security risk when running.
Terminal Services	TermService	svchost.exe	Required for Fast User Switching, Remote Desktop and Remote Assistance	Manual If not required may be Disabled
Themes	Themes	svchost.exe	XP Active Desktop Themes, and quick launch toolbars [ RESOURCE HOG ]	Automatic Set to Manual or Disabled if you dont like themes.
UPS or Uninterruptible Power Supply	UPS	Ups.exe	Support for an Uninteruptable Power Supply (UPS) physically connected to the machine.	Manual Not every UPS will need or use this service.
Universal Plug and Play Host	UPNPhost	svchost.exe	Device Host detect and configure external UPnP devices. UPnP<>PnP	Manual
Upload Manager	uploadmgr	svchost.exe	Upload Manager.	Removed in XP SP2
Volume Shadow Copy	VSS	vssvc.exe	MS Backup - A volume shadow copy is a picture of the volume at a particular moment in time. That means a computer can be backed up while files are open and applications running.	Manual If not required may be disabled see MS Software Shadow Copy Provider Service
WebClient	WebClient	svchost.exe	Allow access to web-resident disk storage from an ISP. WebDAV "internet disks" such as Apple's iDisk.	Automatic If not required may be disabled
Windows Audio	AudioSrv	svchost.exe	Sound Driver Note that disabling the sound driver won't stop sounds from playing - you just won't hear them.	Automatic If no sound card fitted then disable.
Windows Firewall (XP SP2) Internet Connection Firewall (XP) Internet Connection Sharing (Win 2K)	SharedAccess	svchost.exe -k netsvcs	Network address translation, addressing, and name resolution services for all computers on your home network through a dial-up connection.	Automatic. For better protection consider adding a third party firewall.
Windows Image Acquisition	stisvc	svchost.exe	Required for some but not all cameras, scanners, and digital video cameras.	Manual
Windows Installer	MSIServer	MsiExec.exe /V	Install, repair and remove software according to instructions contained in .MSI files.	Manual
Windows Management Instrumentation	WinMgmt	C:\WINNT\System32 \WBEM\WinMgmt.exe	WMI provides system management information.	Automatic
Windows Management Instrumentation Driver Extensions	Wmi	svchost.exe	Provides systems management information to and from drivers.	Manual
Windows Time	W32time	services.exe	Update the computer clock by reference to an internet time source or a time server.	Automatic
Wireless Zero Configuration	WZCSVC	svchost.exe	Configure wireless network devices (802.11a/b/g).	Automatic disable if you don't have any wireless devices.
WMI Performance Adapter	WmiApSrv	wmiapsrv.exe	Collect performance library information.	Manual
Workstation	lanmanworkstation	Services.exe	Communications and network connections. Services dependent on this being started: Alerter, Messenger, and Net Logon.	Automatic

It is inadvisable to disable a service without being aware of the consequences, always start by setting the service to manual, reboot and test for any problems.
A service set to manual may be automatically restarted if another service is dependent on it.
A service set to disabled will not restart even if it's required to boot the machine!
Stopping or disabling a service will generally save a small amount of memory and will reduce the number of software interrupts (cpu message queue.) The main reason for tinkering with services is to harden the system against security vulnerabilities. Disable everything that you don't need or use - then any future problems with those services cannot affect the machine.
To document all the services currently installed:

SC QUERY state= all |findstr "DISPLAY_NAME STATE" >my_services.csv

Some XP services communicate and send data directly to Microsoft, this is not generally something to lose sleep over. Managing the running of these services may be a consideration if confidentiality/anonymity is highly important to you.
Removing a service completely
To delete a service, you may be tempted to hack the registry settings under (HKLM/SYSTEM/CurrentControlSet/Services) this is not a reliable or recommended method, far better is to use the SC command:

SC delete NameofServiceTodelete

Enable or Disable Ports
Many services and applications rely on the use of a specific PORT - to determine if a particular port is enabled for use, review the list of Service names and port numbers held in the "services" file ('windows\system32\drivers\etc\services')
Installing a good firewall is the easiest way to manage this.
"The service we render to others is really the rent we pay for our room on this earth. It is obvious that man is himself a traveler; that the purpose of this world is not 'to have and to hold' but 'to give and serve.' There can be no other meaning." - Sir Wilfred T. Grenfell

Windows XP Command Line Syntax

   Parameters    Command Line Parameters  %1  %~f1

   Variables     Create/read environment variables

   Redirection   Spooling output to a file, piping input

   AND/OR Logic  Conditional Execution (If-Then-Else)

   Loops         Loops and Subroutines

   functions     How to package blocks of code

   Services     List of Windows XP Services

Evaluating expressions

   Using brackets to Group and expand expressions

   Delayed Expansion Manage <xml> and <html> text

   SET /A        Environment variable arithmetic

   VarSubstring  Extract part of a variable (substring)

   VarSearch     Search & replace part of a variable

   Escape chars, delimiters and quotes

   Wildcards     Match multiple files

Batch Files

   DateMath      Add or subtract days from any date

   GetDate.cmd   Get todays date (any region, any OS)

   GetTime.cmd   Get the time now

   GetGMT.cmd    Time adjusted to Greenwich Mean Time

   datetime.vbs  Get Date, Time and daylight savings

   deQuote       Remove quotes from a string

   DelOlder.cmd  Delete files more than n days old

   StampMe.cmd   Rename a file with the date/time

   Which.cmd     Display full path to any command

   DragDrop.cmd  Drag and drop onto a batch script

Reference/How to

   RUN commands   Start-Run Snap-Ins and Control panel applets

   Slow Browsing  Speed up network browsing

   Printing       Printer connections and print drivers

   Qchange        Script to change Printer connections

   Desktop Heap   Memory configuration

   Permissions    Local vs Global workgroups

   Long Filenames NTFS filename issues

   WorkGroups     Built-In Users and Security Groups

   autoexec       Run commands at startup

   Recovery       The Recovery Console

   WinXP Registry   User interface settings

WMI Control overview

Windows Management Instrumentation (WMI) Control is a tool that enables you to configure WMI settings on a remote computer or local computer. Using the WMI Control, you can manage the following tasks remotely.

Authorize users or groups and set permission levels

You can enable an individual user, group, or namespace to access network objects and perform WMI tasks and services. For example, you can enable a group to manage WMI's Common Information Model (CIM) objects on their local computers.

Configure error logging

You can turn error logging on or off and, if turned on, set it to report errors only (the default) or all actions (verbose). Error logging can help you troubleshoot WMI problems. You can also define a maximum size for log files and their folder location.

Back up the repository

You can configure the WMI Control to back up your repository on a regular schedule, or you can do it manually at any time. The repository is the database of objects that you can access through WMI. You can also restore a previous version of the repository.

Change the default namespace for scripting

You can change the default namespace that is targeted in WMI scripts.

Indexing Service

Using Indexing Service

Indexing Service creates indexes of the contents and properties of documents on your local hard drive and on shared network drives. You can also control the information included in the indexes. Indexing Service is designed to run continuously and requires little, if any, maintenance.

To open Indexing Service

1.	Open Computer Management (Local)
2.	In the console tree, double-click Services and Applications.
3.	Double-click Indexing Service.

Note

•	To open Computer Management, click Start, and then click Control Panel. Click Performance and Maintenance, click Administrative Tools, and then double-click Computer Management.
•	For information about using Indexing Service, on the Action menu in Computer Management, click Help.
	Note If you are not comfortable with the information that is presented in this section, ask someone for help or contact support. For information about how to contact support, see the Microsoft Help and Support contact information Web site: http://support.microsoft.com/contactus (http://support.microsoft.com/contactus)

Utility software Software Category

2010-09-06T12:42:00.002+06:00

Utility software is a kind of system software designed to help analyze, configure, optimize and maintain the computer. A single piece of utility software is usually called a utility (abbr. util) or tool.
Utility software should be contrasted with application software, which allows users to do things like creating text documents, playing games, listening to music or surfing the web. Rather than providing these kinds of user-oriented or output-oriented functionality, utility software usually focuses on how the computer infrastructure (including the computer hardware, operating system, application software and data storage) operates. Due to this focus, utilities are often rather technical and targeted at people with an advanced level of computer knowledge.
Most utilities are highly specialized and designed to perform only a single task or a small range of tasks. However, there are also some utility suites that combine several features in one software.
Most major operating systems come with several pre-installed utilities.

Utility software categories

Disk storage utilities
Disk defragmenters can detect computer files whose contents are broken across several locations on the hard disk, and move the fragments to one location to increase efficiency.
Disk checkers can scan the contents of a hard disk to find files or areas that are corrupted in some way, or were not correctly saved, and eliminate them for a more efficiently operating hard drive.
Disk cleaners can find files that are unnecessary to computer operation, or take up considerable amounts of space. Disk cleaner helps the user to decide what to delete when their hard disk is full.
Disk space analyzers for the visualization of disk space usage by getting the size for each folder (including sub folders) & files in folder or drive. showing the distribution of the used space.
Disk partitions can divide an individual drive into multiple logical drives, each with its own file system which can be mounted by the operating system and treated as an individual drive.
Backup utilities can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion).
Disk compression utilities can transparently compress/uncompress the contents of a disk, increasing the capacity of the disk.
File managers provide a convenient method of performing routine data management tasks, such as deleting, renaming, cataloging, uncataloging, moving, copying, merging, generating and modifying data sets.
Archive utilities output a stream or a single file when provided with a directory or a set of files. Archive utilities, unlike archive suites, usually do not include compression or encryption capabilities. Some archive utilities may even have a separate un-archive utility for the reverse operation.
System profilers provide detailed information about the software installed and hardware attached to the computer.
Anti-virus utilities scan for computer viruses.
Hex editors directly modify the text or data of a file. These files could be data or an actual program.
Data compression utilities output a shorter stream or a smaller file when provided with a stream or file.
Cryptographic utilities encrypt and decrypt streams and files.
Launcher applications provide a convenient access point for application software.
Registry cleaners clean and optimize the Windows registry by removing old registry keys that are no longer in use.
Network utilities analyze the computer's network connectivity, configure network settings, check data transfer or log events.
Command line interface (CLI) and Graphical user interface (GUI) Allows the user to contact and make changes to the operating system.

Different Types of Operating Systems

2010-09-06T12:41:00.000+06:00

Operating systems that create a link between users and the applications form the core of computer systems. It dissociates the programs and the hardware and simplifies resource management. Let us look at the different types of operating systems.

An operating system is a software component of a computer system that is responsible for the management of various activities of the computer and the sharing of computer resources. It hosts the several applications that run on a computer and handles the operations of computer hardware. Users and application programs access the services offered by the operating systems, by means of system calls and application programming interfaces. Users interact with operating systems through Command Line Interfaces (CLIs) or Graphical User Interfaces known as GUIs. In short, operating system enables user interaction with computer systems by acting as an interface between users or application programs and the computer hardware. Here is an overview of the different types of operating systems.

Real-time Operating System: It is a multitasking operating system that aims at executing real-time applications. Real-time operating systems often use specialized scheduling algorithms so that they can achieve a deterministic nature of behavior. The main object of real-time operating systems is their quick and predictable response to events. They either have an event-driven or a time-sharing design. An event-driven system switches between tasks based of their priorities while time-sharing operating systems switch tasks based on clock interrupts.

Multi-user and Single-user Operating Systems: The operating systems of this type allow a multiple users to access a computer system concurrently. Time-sharing system can be classified as multi-user systems as they enable a multiple user access to a computer through the sharing of time. Single-user operating systems, as opposed to a multi-user operating system, are usable by a single user at a time. Being able to have multiple accounts on a Windows operating system does not make it a multi-user system. Rather, only the network administrator is the real user. But for a Unix-like operating system, it is possible for two users to login at a time and this capability of the OS makes it a multi-user operating system.

Multi-tasking and Single-tasking Operating Systems: When a single program is allowed to run at a time, the system is grouped under a single-tasking system, while in case the operating system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types namely, pre-emptive or co-operative. In pre-emptive multitasking, the operating system slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking. Cooperative multitasking is achieved by relying on each process to give time to the other processes in a defined manner. MS Windows prior to Windows 95 used to support cooperative multitasking.

Distributed Operating System: An operating system that manages a group of independent computers and makes them appear to be a single computer is known as a distributed operating system. The development of networked computers that could be linked and communicate with each other, gave rise to distributed computing. Distributed computations are carried out on more than one machine. When computers in a group work in cooperation, they make a distributed system.

Embedded System: The operating systems designed for being used in embedded computer systems are known as embedded operating systems. They are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources. They are very compact and extremely efficient by design. Windows CE, FreeBSD and Minix 3 are some examples of embedded operating systems.

The operating systems thus contribute to the simplification of the human interaction with the computer hardware. They are responsible for linking application programs with the hardware, thus achieving an easy user access to the computers.

The History of Computers( Year Wise)

2010-09-03T21:16:00.000+06:00

"Who invented the computer?" is not a question with a simple answer. The real answer is that many inventors contributed to the history of computers and that a computer is a complex piece of machinery made up of many parts, each of which can be considered a separate invention.
This series covers many of the major milestones in computer history (but not all of them) with a concentration on the history of personal home computers.

Computer History Year/Enter	Computer History Inventors/Inventions	Computer History Description of Event
1936	Konrad Zuse - Z1 Computer	First freely programmable computer.
1942	John Atanasoff & Clifford Berry ABC Computer	Who was first in the computing biz is not always as easy as ABC.
1944	Howard Aiken & Grace Hopper Harvard Mark I Computer	The Harvard Mark 1 computer.
1946	John Presper Eckert & John W. Mauchly ENIAC 1 Computer	20,000 vacuum tubes later...
1948	Frederic Williams & Tom Kilburn Manchester Baby Computer & The Williams Tube	Baby and the Williams Tube turn on the memories.
1947/48	John Bardeen, Walter Brattain & Wiliam Shockley The Transistor	No, a transistor is not a computer, but this invention greatly affected the history of computers.
1951	John Presper Eckert & John W. Mauchly UNIVAC Computer	First commercial computer & able to pick presidential winners.
1953	International Business Machines IBM 701 EDPM Computer	IBM enters into 'The History of Computers'.
1954	John Backus & IBM FORTRAN Computer Programming Language	The first successful high level programming language.
1955 (In Use 1959)	Stanford Research Institute, Bank of America, and General Electric ERMA and MICR	The first bank industry computer - also MICR (magnetic ink character recognition) for reading checks.
1958	Jack Kilby & Robert Noyce The Integrated Circuit	Otherwise known as 'The Chip'
1962	Steve Russell & MIT Spacewar Computer Game	The first computer game invented.
1964	Douglas Engelbart Computer Mouse & Windows	Nicknamed the mouse because the tail came out the end.
1969	ARPAnet	The original Internet.
1970	Intel 1103 Computer Memory	The world's first available dynamic RAM chip.
1971	Faggin, Hoff & Mazor Intel 4004 Computer Microprocessor	The first microprocessor.
1971	Alan Shugart &IBM The "Floppy" Disk	Nicknamed the "Floppy" for its flexibility.
1973	Robert Metcalfe & Xerox The Ethernet Computer Networking	Networking.
1974/75	Scelbi & Mark-8 Altair & IBM 5100 Computers	The first consumer computers.
1976/77	Apple I, II & TRS-80 & Commodore Pet Computers	More first consumer computers.
1978	Dan Bricklin & Bob Frankston VisiCalc Spreadsheet Software	Any product that pays for itself in two weeks is a surefire winner.
1979	Seymour Rubenstein & Rob Barnaby WordStar Software	Word Processors.
1981	IBM The IBM PC - Home Computer	From an "Acorn" grows a personal computer revolution
1981	Microsoft MS-DOS Computer Operating System	From "Quick And Dirty" comes the operating system of the century.
1983	Apple Lisa Computer	The first home computer with a GUI, graphical user interface.
1984	Apple Macintosh Computer	The more affordable home computer with a GUI.
1985	Microsoft Windows	Microsoft begins the friendly war with Apple.
SERIES	TO BE	CONTINUED

Short History about IBM Computer and DOS Operating System

2010-09-03T21:14:00.000+06:00

The History of the IBM PC - International Business Machines

In July of 1980, IBM representatives met for the first time with Microsoft's Bill Gates to talk about writing an operating system for IBM's new hush-hush "personal" computer. IBM had been observing the growing personal computer market for some time. They had already made one dismal attempt to crack the market with their IBM 5100. At one point, IBM considered buying the fledgling game company Atari to commandeer Atari's early line of personal computers. However, IBM decided to stick with making their own personal computer line and developed a brand new operating system to go with. The secret plans were referred to as "Project Chess". The code name for the new computer was "Acorn". Twelve engineers, led by William C. Lowe, assembled in Boca Raton, Florida, to design and build the "Acorn". On August 12, 1981, IBM released their new computer, re-named the IBM PC. The "PC" stood for "personal computer" making IBM responsible for popularizing the term "PC".The first IBM PC ran on a 4.77 MHz Intel 8088 microprocessor. The PC came equipped with 16 kilobytes of memory, expandable to 256k. The PC came with one or two 160k floppy disk drives and an optional color monitor. The price tag started at $1,565, which would be nearly $4,000 today. What really made the IBM PC different from previous IBM computers was that it was the first one built from off the shelf parts (called open architecture) and marketed by outside distributors (Sears & Roebucks and Computerland). The Intel chip was chosen because IBM had already obtained the rights to manufacture the Intel chips. IBM had used the Intel 8086 for use in its Displaywriter Intelligent Typewriter in exchange for giving Intel the rights to IBM's bubble memory technology.
Less than four months after IBM introduced the PC, Time Magazine named the computer "man of the year"

The History of the MS-DOS Operating Systems, Microsoft, Tim Paterson, and Gary Kildall

On August 12, 1981, IBM introduced its new revolution in a box, the "Personal Computer" complete with a brand new operating system from Microsoft and a 16-bit computer operating system called MS-DOS 1.0.

Operating System : /n./ [techspeak] (Often abbreviated `OS') The foundation software of a machine, of course; that which schedules tasks, allocates storage, and presents a default interface to the user between applications. The facilities an operating system provides and its general design philosophy exert an extremely strong influence on programming style and on the technical cultures that grow up around its host machines. - The Jargon Dictionary*
In 1980, IBM first approached Bill Gates and Microsoft, to discuss the state of home computers and Microsoft products. Gates gave IBM a few ideas on what would make a great home computer, among them to have Basic written into the ROM chip. Microsoft had already produced several versions of Basic for different computer system beginning with the Altair, so Gates was more than happy to write a version for IBM.As for an operating system (OS) for the new computers, since Microsoft had never written an operating system before, Gates had suggested that IBM investigate an OS called CP/M (Control Program for Microcomputers), written by Gary Kildall of Digital Research. Kindall had his Ph.D. in computers and had written the most successful operating system of the time, selling over 600,000 copies of CP/M, his OS set the standard at that time

IBM tried to contact Kildall for a meeting, executives met with Mrs. Kildall who refused to sign a non-disclosure agreement. IBM soon returned to Bill Gates and gave Microsoft the contract to write the new operating system, one that would eventually wipe Kildall's CP/M out of common use.

The "Microsoft Disk Operating System" or MS-DOS was based on QDOS, the "Quick and Dirty Operating System" written by Tim Paterson of Seattle Computer Products, for their prototype Intel 8086 based computer.QDOS was based on Gary Kildall's CP/M, Paterson had bought a CP/M manual and used it as the basis to write his operating system in six weeks, QDOS was different enough from CP/M to be considered legal.Microsoft bought the rights to QDOS for $50,000, keeping the IBM deal a secret from Seattle Computer Products.Gates then talked IBM into letting Microsoft retain the rights, to market MS DOS separate from the IBM PC project, Gates proceeded to make a fortune from the licensing of MS-DOS.In 1981, Tim Paterson quit Seattle Computer Products and found employment at Microsoft.

Access to various networks on Linux

2010-09-03T20:48:00.000+06:00

Big corporations often sub-divide their networks into small networks, hidden behind gateways. To access
them, you need to tell your Linux system that there is a gateway to use to access the networks.
The route program makes it easy to add networks, hosts and gateways to your routing table. To add a default
gateway, for example to access the Internet, you can set it as default with the following line:
route add default gw 10.0.0.1
This will work if you need to access the Internet via the 10.0.0.1 gateway. Now, if you want to access
networks 10.1.0.0 and 10.2.0.0 through other gateways, here is what you will want to do:
route add -net 10.1.0.0 gw 10.0.0.10
route add -net 10.2.0.0 gw 10.0.0.20

Changing file permissions on Linux Operating System

2010-09-03T20:38:00.002+06:00

To change a file's permissions, you need to use a program called chmod. With that command you can change
one or multiple file permissions. Here are a few examples:
$ chmod 755 file
$ ls -l file
-rwxr-xr-x 1 root users 1656 Mar 22 00:27 file
$ chmod 700 file
$ ls -l file
-rwx------ 1 root users 1656 Mar 22 00:27 file
$ chmod 664 file
$ ls -l file
-rw-rw-r-- 1 root users 1656 Mar 22 00:27 file
The numbers are based on the 3 types of permissions. Read = 4, write = 2 and execute = 1. A permission of
755 means the user will have read, write and execute permissions (4 + 2 + 1 = 7), and everyone else will have
read and execute permissions (4 + 1 = 5).

Mouse problems(in Linux OS)

2010-09-03T14:42:00.002+06:00

The mouse is a very important part of a computer. In X, you can't do much without it. Even in console some
applications will allow you to use it. You must first configure it.
Like every other device, the mouse has a device file in the /dev directory. Depending on your mouse type, it
will be either /dev/psaux for a PS/2 mouse, or /dev/cua0 for a serial mouse on COM1.
To make it easy to use in the future, you should link the right device file to /dev/mouse:
ln -s /dev/cua0 /dev/mouse
Then, when you configure X Window or any other program that requires a mouse, you can specify
/dev/mouse.

TV on Linux

2010-09-03T14:40:00.002+06:00

A number of cards exist allowing you to watch and record TV on your PC. Most come with software for
Windows only, like so many things, but it is possible to do the same thing on Linux.
Linux comes with several drivers which make up the Video4Linux drivers. Several cards are supported by
these drivers, and a list of them is available at http://roadrunner.swansea.linux.org.uk/v4l.shtml. This is the
driver side. You also need software to use the devices.
Several programs are available to watch TV, capture images and even Web applications. A list of some of the
programs is available at http://www.thp.uni-koeln.de/~rjkm/linux/bttv.html including datasheets

Linux without a hard drive

2010-09-03T14:37:00.003+06:00

Modern Linux distributions require around 100 megs to 200 megs of hard disk space to install. But is it
possible to run Linux on a system without a hard drive? Yes it is.
The Linux Router Project is a full-featured Linux distribution that fits on one diskette. It was made for
routers, and use modules to add the software packages you need, including DNS servers, Web servers, email
and routing. You can find more information on the Linux Router Project at http://www.linuxrouter.org

Can't mount root fs(Linux OS)

2010-09-03T14:37:00.000+06:00

When you boot a system, this is an error that will halt the system. This error means that the kernel can't
mount the root file system, so it can't get all of its configuration files.
There are a few cases where this happens:
· No IDE support in the kernel. If your main hard drive is an IDE, and you have recompiled
without including "Enhanced IDE/MFM/RLL disk/cdrom/tape/floppy support" or some other
basic IDE device drivers.
· File system not supported. Usually the root file system should be of type ext2. You need to
make sure that ext2 is compiled in the kernel, and not as a module because you can't load
modules without first mounting the root file system.
· The drive is not ready. If you have removed the drive, the hard disk died or the BIOS didn't
detect the device for some reason, then the kernel won't be able to mount it.

Use Windows special keys in Linux

2010-09-03T14:34:00.002+06:00

Why are all the new keyboards sold with Win95 keys on them? How about making them do real keyboard
functions while in X Window? Here is how.
First you need to find out which key mapping you are using. Usually it will be US, it might also be en_US, ca
or else. Locate the file, usually in /usr/X11/lib/X11/xkb and edit it with your favorite editor. For me the file is
called /usr/X11/lib/X11/xkb/symbols/ca.
The file lists all the key codes and what they do. The key codes for the Win95 special keys are LWIN, RWIN
and MENU. All you need to do is add them to the list, with the functions for them. I decided to map the left
WIN key to "@" and the right WIN key and MENU keys to "{" and "}". Here are the lines I added:
key <RWIN> { [ braceleft ] };
key <LWIN> { [ at ] };
key <MENU> { [ braceright ] };
By browsing the file you can find all the other symbols and what they do. You can also add multiple
functions to a key, by using ALT and SHIFT.
The changes will take effect when you restart X Window. With the XKB extension (you do need to have it
enabled in /etc/XF86Config btw) it's easy to change the mapping of any key.

Making CD-ROM images(Linux OS)

2010-09-03T14:33:00.002+06:00

With other operating systems, such as Microsoft Windows or IBM OS/2, you are not allowed in the license to
make your own CD-ROM with the OS on it and then distribute it.
Linux, being Open Source and free, can be copied. You can download a distribution or buy it from an online
store and burn your own copy, and then install it on many computers, or give it to your friends. Usually, you
will find instructions on how to do that on the FTP server for your favorite distribution. You will need the
main directory on the CD-ROM. The sources are not needed since they are available from the FTP site.
Some distributions also come with ISO images of their CD-ROM. This is a single file that can be put onto a
CD-ROM, and will create a full file system with files on it.
One thing you have to be careful is not to copy commercial programs. The basic CD-ROM where the Linux
distribution is located is composed of free software. But some distributions may come with other commercial
programs, and you should read the license first.

LILO and boot problems(Linux OS)

2010-09-03T14:31:00.002+06:00

When a computer starts, the number of beeps the BIOS outputs tells you the state of the computer. On some
computers, one beep means all is ok, but 2 beeps mean there is an error. LILO uses the same kind of codes.
The number of letters you see from the word LILO on the screen says what is wrong. The whole word means
everything is fine, only LI means only the first part of LILO could be loaded. A full description of this is
available from the Bootdisk HOWTO.
When LILO can't load, it's a major problem. This often means that the boot code was corrupted. The only
way to boot is from a floppy disk. In RedHat, you can use the rescue disk, in Slackware, you can use the boot
disk with the "mount" image.
When LILO is fine, it's often easier to figure a boot problem. If the kernel panics when it tries to boot, it is
usualy due to a configuration error. You can tell LILO to mount another kernel you may have, like a "safe" or
"old" image you kept for these cases. If the problem is in initialization scripts, you can tell LILO to boot
directly into a shell with the following boot command line:
LILO boot: linux init=/bin/sh
Where "linux" would be your kernel image

Default boot mode(Linux OS)

2010-09-03T14:29:00.002+06:00

When a Linux system boots, it loads the kernel, all its drivers, and the networking servers, then the system
will display a text login prompt. There, users can enter their user names and their passwords. But it doesn't
have to boot this way.
There are 3 modes defined in most Linux distributions that can be used for booting. They are defined in
/etc/inittab and have specific numbers. The first mode, also called runlevel 1, is single user mode. That mode
will only boot the system for 1 user, with no networking. Runlevel 3 is the default mode. It will load the
networking servers and display a text login prompt. Runlevel 5 is the graphical mode. If you have X Window
installed and configured, you can use it to display a graphical login prompt.
The way to change this is to edit /etc/inittab and change the initdefault line:
id:3:initdefault:
Changing a 3 to a 5 will make the system display a xdm graphical screen on bootup

Default file permissions(Linux OS)

2010-09-03T14:25:00.000+06:00

When you create a file, the system gives it default permissions. On most systems the permissions are 755
(read, write and execute for the owner, and read and execute for others).
This default is setup with the umask command. To use the command, you need to find the right octal number
to give it. The permissions in the umask are turned off from 666. This means that a umask of 022 will give
you the default of 755. To change your default permissions from 755 to 700, you would use this command:
umask 077

Annoying boot messages(linux OS)

2010-09-03T14:23:00.002+06:00

When recompiling your kernel, you might end up seeing strange messages on bootup like:
modprobe: cannot find net-pf-5
modprobe: cannot find char-major-14
These are messages from the modules loader telling you that he can't find specific modules. This usualy
happens when you compile modules, but modprobe tries to load modules that were not compiled and it can't
find them. The way to remove those messages is to set the modules to off. In the file /etc/conf.modules you
may want to add:
alias net-pf-5 off
alias char-major-14 off
This will stop modprobe from trying to load them. Of course you could also try to resove the problem by
compiling the modules and make sure modprobe knows where they are.

Allowing users to run root programs(linux OS)

2010-09-03T14:21:00.003+06:00

When a user starts a command, it runs with the permissions of that user. What if you want to allow them to
run some commands with root permissions? You can, and that's called suid.
You can set a command to be suid root with the chmod command. This will make it run as root even if a user
starts it. Here is how to set mybin suid root:
chmod +s mybin
Note that you must be very careful with this option. If the command has any security hole, or allows the user
to access other files or programs, the user could take over the root account and the whole system.

Allowing users to mount drives(Linux)

2010-09-03T14:21:00.000+06:00

By default, Linux will not allow users to mount drives. Only root can do it, and making the mount binary suid
root is not a good idea. With a special command in the /etc/fstab file, you can change that.
This is a typical line for the fd0 (A:) drive in /etc/fstab:
/dev/fd0 /mnt auto noauto,user 1 1
The keywords here are noauto and user. Noauto tells mount not the try to mount a diskette on boot, and user
allows any user to mount the drive into /mnt. The auto keyword is also interesting. It tells mount to try to find
out which file system is on the diskette. You could also use msdos or ext2.

Master boot record and LILO

2010-09-03T14:19:00.001+06:00

What is the master boot record (MBR) and why does LILO erase the old boot loader? Every hard drive has a
top space called the MBR where the BIOS will try to load an operating system. Every system has its own
loader. DOS has DOS-MBR, Windows NT has the NTLDR and Linux has LILO.
When you install LILO, you can install it in the MBR or in a boot record for the Linux partition. If you want
to keep your current boot loader, you can select the Linux partition, and make sure it is the active partition in
fdisk. This way you will be able to boot to LILO, and then boot the old loader from the MBR.
If you plan on only using Linux on your system, you can tell LILO to boot right into Linux and not display a
"boot:" prompt, and you can install it in the MBR.

Wrong memory size found in Linux

2010-09-03T14:18:00.002+06:00

The Linux kernel will detect various settings from your computer configuration. This includes the size of
memory you have. In some cases, it will find the wrong size. For example, it could find only 64 megs of
memory when in fact you have 128 megs.
The trick here is to specify the amount of RAM memory you have with the "mem=" parameter. Here is what
you would type when your system boots if you have 128 megs of memory:
LILO boot: linux mem=128M
This will tell LILO to load the linux kernel with 128 megs of memory

The boot prompt

2010-09-03T14:16:00.002+06:00

The Linux system uses a program called LILO to boot itself. This is the LInux LOader, and will load a kernel
and can pass various parameters. This is what the "boot:" prompt is for.
At the "boot:" prompt, you can enter a lot of parameters. You can send parameters to drivers like the ethernet
driver, telling it at which IRQ the ethernet card is located, or you can pass parameters to the kernel, like
memory size or what to do in a panic. Reading the LILO manual will tell you all of the nice things LILO can
be used for.
Note that for device drivers compiled as modules, you need to pass values when you load these drivers, and
not on the "boot:" prompt.

Swap and memory

2010-09-03T14:15:00.000+06:00

One important setting in any protected mode operating system like Linux is the swap space. In the
installation, you will need to create a swap partition. A common question is what size should the partition be?
The proper size depends on 2 things: The size of your hard drive and the size of your RAM memory. The less
RAM you have, the more swap you will need. Usually you will want to set your swap space size to be twice
the RAM size, with a maximum of 128 megs. This of course requires you to have a hard drive with enough
free space to create such a partition.
If you have 16 megs of RAM, making the swap space 32 megs or even 64 megs is very important. You will
need it. If you have 128 megs of RAM on the other hand, you won't need much swap because the system will
already have 128 megs to fill before using swap space. So a swap partition of 128 megs or even 32 megs
could be enough.
If you don't select enough swap, you may add more later.

More swap with a swap file

You installed a new Linux system, but forgot to set enough swap space for your needs. Do you need to
repartition and reinstall? No, the swap utilities on Linux allow you to make a real file and use it as swap
space.
The trick is to make a file and then tell the swapon program to use it.
Here's how to create, for example, a 64
megs swap file on your root partition (of course make sure you have at least 64 megs free):
dd if=/dev/zero of=/swapfile bs=1024 count=65536
This will make a 64 megs (about 67 millions bytes) file on your hard drive. You now need to initialize it:
mkswap /swapfile 65536
sync
And you can then add it to your swap pool:
swapon /swapfile
With that you have 64 megs of swap added. Don't forget to add the swapon command to your startup files so
the command will be repeated at each reboot.