Computing Tech

Recovering WSS Data Using SharePoint 3.0 Central Administration

noreply@blogger.com (Computing Tech) — Tue, 31 Jan 2012 07:35:00 PST

If a previous WSS backup was performed using the SharePoint 3.0 Central Administration tool, recovery can be performed using this tool as well. To recover WSS using a SharePoint 3.0 Central Administration backup, perform the following steps:

1. Log on to the Windows Server 2008 R2 Windows SharePoint Services server system with an account with administrator privileges.

2. Click Start, click All Programs, click Administrative Tools, and select SharePoint 3.0 Central Administration.

3. When the browser opens, if prompted, enter a username and password for an account with administrative privileges on the WSS server.

4. When the SharePoint 3.0 Central Administration website opens, select the Operations tab.

5. In the window, scroll down; on the right side, in the Backup and Restore section, click on the Restore from backup option.

6. Near the top of the window, enter the UNC network path of the backup, and click OK. For example, enter \\server30\wssbackup\ and click OK.

7. On the next page, select the desired backup by selecting the appropriate option button, and click the Continue Restore Process link.

8. On the next page, select the appropriate databases or components of the WSS farm that will be restored by checking the appropriate check boxes, and then click the Continue Restore Process link. For this example, the entire farm will be restored by clicking the check box next to Farm.

9. On the next page, in the Type of Restore section, select the Same Configuration option button because you are trying to restore an existing system back to a functional state. When this option button is selected, a window opens stating that the selected objects will be overwritten with the data from the restore; click OK to continue.

10. Scroll to the bottom of the page, and click OK to submit the restore job to the SharePoint Services Timer Service.

11. You will be directed to the Backup and Restore Status page. Click the Refresh link to view and get updates on the status of the job.

12. After the job completes, open the restored SharePoint sites and check functionality. IIS might need to be restarted, and if the system can tolerate a system reboot, it might be helpful in case other dependent services are not running because of SharePoint issues.

13. If WSS is restored back to normal operation, run a full backup and log off.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Active Directory Authoritative Restore

noreply@blogger.com (Computing Tech) — Thu, 26 Jan 2012 05:29:00 PST

When Active Directory has been modified and needs to be restored to a previous state, and this rollback needs to be replicated to all domain controllers in the domain and possibly the forest, an authoritative restore of Active Directory is required. An authoritative restore of Active Directory can include the entire Active Directory database, a single object, or a container, such as an organizational unit including all objects previously stored within the container. To perform an authoritative restore of Active Directory, perform the System State restore of a domain controller, but when you are finished, reboot as directed and when the reboot completes follow these additional steps:
1. Open a command prompt on the domain controller that is running in DSRM and has just completed a System State recovery and a reboot.

2. In the Command Prompt window, type NTDSUTIL and press Enter.

3. Type Activate Instance NTDS and press Enter.

4. Type Authoritative Restore and press Enter.

5. To restore a single object, type Restore Object followed by the distinguished name of the previously deleted object. For example, to restore an object named Khalil Droubi in the Users container of the companyabc.com domain, type Restore Object “cn=Khalil Droubi,cn=users,dc=companyabc,dc=com”.

6. To restore a container or organizational unit and all objects beneath it, replace the “restore object” with “restore subtree” followed by the appropriate distinguished name.

7. After the appropriate command is typed in, press Enter. A window opens, asking for confirmation of the authoritative restore; click the Yes button to complete the authoritative restore of the object or subtree.

8. The NTDSUTIL tool displays the name of the text file that may contain any backlinks for objects just restored. Note the name of the file(s) and whether any backlinks were contained in the restored objects.

9. Type quit and press Enter; type quit again to close out of the NTDSUTIL tool.

10. Click the Restart button in the Windows Server Backup dialog box and reboot. Make sure to set the boot option back to normal boot if not changed previously.

11. After the domain controller reboots into normal boot mode, log on to verify that the authoritatively restored objects are replicating to the other domain controllers. If things are working properly, run a full backup of the domain controller and log off.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

System State Recovery for Domain Controllers

noreply@blogger.com (Computing Tech) — Tue, 24 Jan 2012 05:26:00 PST

Performing a System State recovery for a domain controller is similar to the recovery of a member server, but a few more options are presented during the selection process and the domain controller needs to be booted into Directory Services Restore mode. Recovering the System State of a domain controller should only be performed if objects were deleted from Active Directory and need to be restored and the Active Directory Recycle Bin is not enabled, or if the Active Directory database on the particular domain controller is corrupt and the Active Directory Domain Services service will not start properly, or if data in the SYSVOL is missing or corrupted and needs recovery.
Before a domain controller can be booted into DSRM, the DSRM password will be required. This password is configured when a system is promoted to a domain controller and is stored locally on each domain controller. The DSRM username is administrator with no domain designation and the password can manually be changed on a working domain controller by using the NTDSUTIL utility. To restore the System State of a domain controller, perform the following steps:

1. Log on to the Windows Server 2008 R2 domain controller system with an account with administrator privileges.

2. Click Start, click All Programs, click Administrative Tools, and select System Configuration.

3. Select the Boot tab. In the Boot Options section, check the Safe Boot check box, select the Active Directory Repair option button, and then click OK.

4. The System Configuration utility will ask for a reboot, and if there are no additional tasks to perform, click the Restart button to boot the system into DSRM.

5. When the system completes a reboot, log on as administrator with the DSRM password. Make sure to specify the local server as the logon domain—for example, server10\administrator instead of companyabc\administrator.

6. Click Start, click All Programs, click Administrative Tools, and select Windows Server Backup.

7. In the Actions pane, select Recover to start the Recovery Wizard.

8. On the Getting Started page, select This Server (Servername), where Servername is the name of the server to which Windows Server Backup is connected, and click Next to continue.

9. On the Select Backup Date page, select the correct date and time of the backup you will use to restore the data, and click Next to continue. Days with a successful backup are formatted in boldface.

10. On the Select Recovery Type page, select the System State option button, and click Next to continue.

11. On the Select Location for System State Recovery page, select the Original Location option button. Do not check the Perform an Authoritative Restore of Active Directory Files check box unless the sysvol folder and content will be marked as the definitive/authoritative copy and replicated to all other domain controllers. For our example, we will recover the System State but not mark the SYSVOL as an authoritative restore. Click Next to continue.

12. A dialog box opens that states that this recovery option will cause the server to resynchronize after recovery; click OK to continue.

13. On the Confirmation page, verify that the System State is listed and that the check box to automatically reboot the server is not checked. Click Recover to start the System State recovery of the domain controller.

14. A dialog box opens, detailing that once the recovery is started, it cannot be paused, and a restart will be required to complete the recovery. Click Yes to start the recovery. System State recovery can take a long time to complete; please be patient.

15. Once the System State restore completes, even if the check box to automatically reboot is not checked, Windows Server Backup will present a dialog box with a Restart button and no other option. Restart the server now.

16. Once the server reboots, it will reboot into DSRM again. Log on with the DSRM local username and password.

17. Once logged in, a wbadmin command prompt opens, stating that the restore completed successfully. Close the command prompt.

18. Click Start, click All Programs, click Administrative Tools, and select System Configuration.

19. Select the Boot tab. In the Boot Options section, uncheck the Safe Boot check box and click OK.

20. If an authoritative restore of Active Directory objects is not required, click the Restart button in the dialog box and allow the server to reboot normally.

21. If an authoritative restore is required, click the Exit Without Restart button in the dialog box.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Active Directory Recycle Bin Recovery

noreply@blogger.com (Computing Tech) — Sun, 22 Jan 2012 05:14:00 PST

If you need to recover a deleted Active Directory object and the Active Directory Recycle Bin was not enabled before the object was deleted, skip this section. Now if the Active Directory Recycle Bin feature was enabled before an Active Directory object was deleted, follow the proceeding steps to recover objects using the Active Directory Recycle Bin. Before completing the following steps, you should know a few important things:

» Restoring a deleted object using the Recycle Bin requires that the object’s distinguished name or object GUID is known.

» When restoring an object, the object will be restored into the original location, unless the –TargetPath option is used. If the original location does not exist, the restore will fail.

» Restoring a container or organizational unit using the Restore-ADObject cmdlet does not restore any objects that were contained within the container or OU when it was deleted. For this functionality, either all objects need to be restored after the container or OU is restored or a domain controller can be booted into DSRM and an authoritative restore can be performed using the Restore Subtree option.

Now, if you know that an object was mistakenly deleted and it should be recovered, the following steps can be followed. For this example, we will restore a user account named Khalil Droubi. To discover the properties of this deleted object, we will use the Get- ADObject cmdlet and will filter based on the name of Khalil. Also, when running the Get-AdObject cmdlet, using the –properties switch will expand the attributes listed for the query or search results. To restore a single deleted user object, perform the following steps:

1. Log on to the Windows Server 2008 R2 domain controller system with an account with domain administrator privileges.

2. Click Start, click All Programs, click Accessories, click the Windows PowerShell folder, right-click on Windows PowerShell, and select Run As Administrator.

3. Type cd \ and press Enter.

4. Type Import-Module ActiveDirectory and press Enter.

5. Type Get-Command *AD* -CommandType cmdlet and press Enter. This returns all of the Active Directory-related cmdlets and also returns a few more cmdlets not related to Active Directory.

6. Type Get-ADObject –Searchbase “CN=Deleted Objects,DC=Companyabc,DC=com”
–Filter * -IncludeDeletedObjects and press Enter. This returns all of the deleted
Active Directory objects on the local domain controller in the companyabc.com
domain to the PowerShell window with a default list of attributes.

7. Because we are trying to restore a deleted user account named Khalil Droubi, we can filter the previous command by typing Get-AdObject –Searchbase”CN=Deleted
Objects,DC=Company,DC=com” –LdapFilter “Name=*Khalil*”
–IncludeDeletedObjects and pressing Enter. This command returns all of the deleted objects that contain Khalil in the name.

8. As stated previously, if the deleted object will be restored to the original location, as is the case with a default Restore-ADObject command, the parent OU or container
must be present. To determine the parent container of the deleted user object, type
Get-AdObject –Searchbase”CN=Deleted Objects,DC=Company,DC=com” –LdapFilter
“Name=*Khalil*” –IncludeDeletedObjects –Properties LastknownParent and then press Enter.

9. When the LastKnownParent property value is returned, if the value returns a proper distinguished name, it exists. If the name includes CN=Deleted Objects in the value, the parent OU or container has also been deleted. If the LastKnownParent has been deleted, it either needs to be restored before the deleted user object or the user object needs to be restored to an alternate location using the –TargetPath option in the Restore-ADObject cmdlet.

10. Assuming that the LastKnownParent value returns an existing container to restore the object, copy the ObjectGUID of the deleted user account to the Clipboard, type Restore-ADObject –Identity and paste the ObjectGUID, and press Enter to restore the object.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Checking Out Other IaaS Companies

noreply@blogger.com (Computing Tech) — Wed, 18 Jan 2012 07:32:34 PST

We spend a good deal of time in this chapter describing Amazon’s EC2 because it’s the best known of the IaaS operations. However, it’s by no means the only one. Companies that have entered the IaaS market include Rackspace Cloud, GoGrid, MediaTemple, GridLayer, Flexiscale, and Joyent. All of these, like Amazon, offer a pay-per-use arrangement, with the prices, capabilities, and terms of usage varying.

The services they provide are similar to EC2 as well in that they provide access to a resource pool and enable the configuration of virtual servers and the installation of platform software and Web server software in a simple way. Their approaches vary.

These companies (and others not mentioned) will inevitably be joined by major IT companies such as IBM, Hewlett-Packard, Cisco, EMC, Microsoft, Oracle, CSC, and Accenture, all of whom are strategizing and some of whom are building data centers and preparing to enter the market.

Rackspace
Rackspace Cloud, a spinoff from Rackspace, for example, entered the market in 2005 before Amazon did and offers a service that is much closer to an ISP service than Amazon’s.

It focuses primarily on attracting customers that want to host Web sites and its charges are more oriented to Web site usage. It charges for

✓ Storage space
✓ Bandwidth usage
✓ Compute cycles (which constitute its own measure of CPU and memory usage)

However, it also offers “instant servers” that can be bought on an hourly basis with prices based on memory used and instant storage.

This service is for companies that might want to gradually move their whole operation into the cloud (assuming that all their software can run on commodity servers — no-frills servers designed for basic workloads or servers grouped in clusters to provide lots of computing power through virtualization).

GoGrid
GoGrid has similar pricing to Rackspace, charging for

✓ Storage space (more than 10GB)
✓ Outbound data transfer
✓ Server RAM hours (with different prices for different combinations of memory and CPU)

GoGrid emphasizes ease of use and offers a greater level of technical control (including load balancing) than either the Amazon EC2 or Rackspace cloud.

Others
Many other companies are entering the IaaS market. Here are a few:
✓ MediaTemple is a highly successful ISP that’s turning its hand to IaaS, but continuing with ISP-type pricing.

✓ Gridlayer is a grid computing company that has more than 12,000 servers deployed. It offers virtual private servers, storage, and virtual private data centers. The virtual private data center is what it sounds like — a collection of server resources that can be configured according to need.

✓ Flexiscale is like most of the IaaS companies already described, although it distinguishes itself by providing an API to its environmental software (which most companies don’t). It also provides a virtual LAN (VLAN) to each customer. It claims to be significantly less expensive than Amazon EC2, although it’s clear from the pricing that other IaaS companies may come in less expensive than Amazon EC2, depending on your needs.

✓ Joyent Accelerator is an ISP that has moved into the IaaS market and its pricing (based on a monthly fee for specific levels of hardware) reflects that. Its Zeus Accelerator is a virtual appliance that manages Web applications to guarantee performance. Joyent also has specific expertise in most Web platforms, including Ruby on Rails.

Source of Information : cloud computing for dummies 2010 retail ebook distribution

Windows Server 2008 R2 System State Recovery

noreply@blogger.com (Computing Tech) — Wed, 18 Jan 2012 05:09:00 PST

When operating systems become corrupt or unstable or a role service needs to be rolled back to a previously backed-up state, the quickest and easiest way to perform this task is to restore the System State. The System State can be backed up independently but is also contained within a full server backup. To restore the System State on a Member Server from a previous backup, perform the following steps:

1. Log on to the Windows Server 2008 R2 system with an account with administrator privileges.

2. Click Start, click All Programs, click Administrative Tools, and select Windows Server Backup.

3. In the Actions pane, select Recover to start the Recovery Wizard.

4. On the Getting Started page, select either to restore data previously backed up from the local computer or a different computer. For this example, select This Server (Servername), where Servername is the name of the server Windows Server Backup is connected to, and click Next to continue.

5. On the Select Backup Date page, select the correct date and time of the backup you will use to restore the data, and click Next to continue. Days with a successful backup are formatted in boldface.

6. On the Select Recovery Type page, select the System State option button, and click Next to continue.

7. On the Select Location for System State Recovery page, click the Original Location option button and click Next to continue. If this system was a domain controller, more options would be available.

8. On the Confirmation page, review the section and ensure that the check box to automatically reboot the server to complete the recovery process is checked, and then click Recover to start the process.

9. After the system reboots, log on to the server to verify functionality. If the system is working properly, perform a full system backup.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

System Volume Recovery Using Network Shared Folder Backups

noreply@blogger.com (Computing Tech) — Sat, 14 Jan 2012 05:06:01 PST

If the backup data is stored on a network shared folder, alternate recovery steps are required to restore the system volume. If recovering a system volume from a network shared folder, perform the following steps:

1. Boot up your system using the Windows Server 2008 R2 installation media. If necessary, configure the BIOS to allow booting from the CD/DVD drive and, if prompted, press a key to boot from the DVD.

2. When the Install Windows interface opens, select the correct language, time, and keyboard settings, and click Next to continue.

3. On the next page, click the Repair Your Computer link located in the lower-left corner of the window.

4. On the System Recovery Options page, the operating system drive that will be recovered should be listed. If not, click the Load Drivers button, and install the necessary hard drive controller files. If the system is listed, select the Restore Your Computer Using a System Image That You Created Earlier option button located at the bottom of the window, and click Next to continue.

5. If there is no local backup disk or volume, an error window will appear; click Cancel. On the Select a System Image Backup page, click the Select a System Image option button and click Next.

6. On the Select the Location page, click the Advanced button.

7. In the pop-up window, click on the Search for a System Image on the Network button and confirm that you want to connect to the network and understand the security implications.

8. Enter the UNC path to the network shared folder and click OK. When prompted, enter the appropriate network credentials to access the backup folder.

9. Once connected, the window will list the backup stored on the specified network folder. Select this backup and click Next to continue.

10. The following page lists which volumes are contained within the known backups. Select the desired backup again and click Next to continue.

11. On the Choose Additional Restore Options page, check the Only Restore System Drives check box, and click Next to continue. This leaves any other disks intact, but any volumes that are hosted on the same disks that contain system volumes will be formatted, re-created, and restored as well.

12. The next page details the date and time of the backup that will be restored, the server that will be restored, and the volumes that are contained in this restore set. Review the information and click Finish to continue with the recovery of the system volumes.

13. A dialog box appears stating that all drives selected will be restored with the data in the system image; click Yes to approve this and continue.

14. The recovery time frame will vary depending on the size of the system volume, the performance of the volume, and the restore disk or network share. After the recovery completes, the system will automatically reboot.

15. After the system reboots, log on and verify functionality. If everything is back up and running, run a full backup and log off.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Windows Server 2008 R2 System Volume Recovery

noreply@blogger.com (Computing Tech) — Tue, 10 Jan 2012 05:02:01 PST

Restoring a system volume cannot be performed using Windows Server Backup. System volumes can only be restored using the Windows recovery environment from the Windows installation media. System volumes should only be restored separately when the system volume is corrupted or failed but the system hardware has not changed and data disks remain intact. Any Windows disk that contains system volumes will be erased and restored as part of this process. If a single disk contains two volumes including the system volume and a separate data volume, the data volume will also be erased and restored by this process. To restore the system volume, perform the following steps:
1. Boot up your system using the Windows Server 2008 R2 installation media. If necessary, configure the BIOS to allow booting from the CD/DVD drive and, if prompted, press a key to boot from the DVD.

2. When the Install Windows interface opens, select the correct language, time, and keyboard settings, and click Next to continue.

3. On the next page, click the Repair Your Computer link located in the lower-left corner of the window.

4. On the System Recovery Options page, the operating system drive that will be recovered should be listed. If not, click the Load Drivers button, and install the necessary hard drive controller files. If the system is listed, select the Restore Your Computer
Using a System Image That You Created Earlier option button located at the bottom of the window, and click Next to continue.

5. On the Select a System Image Backup page, if a local disk was used for the backup, the most recent backup will be listed and the Use the Latest Available System Image check box will be automatically selected by default. Select the Select a System Image option button and click Next to continue.

6. The next page presents the list of backups stored on the local dedicated backup disk. Select the desired backup and click Next to continue.

7. The following page lists which volumes are contained within the known backups. Select the desired backup again and click Next to continue.

8. On the Choose Additional Restore Options page, check the Only Restore System Drives check box, and click Next to continue. This leaves any other disks intact, but any volumes that are hosted on the same disks that contain system volumes will be formatted, re-created, and restored as well.

9. The next page details the date and time of the backup that will be restored, the server that will be restored, and the volumes that are contained in this restore set. Review the information and click Finish to continue with the recovery of the system volumes.

10. A dialog box appears, stating that all drives selected will be restored with the data in the system image; click Yes to approve this and continue.

11. The recovery time frame will vary depending on the size of the system volume, the performance of the volume, and the restore disk or network share. After the recovery completes, the system will automatically reboot.

12. After the system reboots, log on and verify functionality. If everything is back up and running, run a full backup and log off.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Windows Server 2008 R2 Data Volume Recovery

noreply@blogger.com (Computing Tech) — Fri, 06 Jan 2012 04:54:00 PST

When a data volume on a Windows Server 2008 R2 system has failed and needs to be restored using Windows Server Backup, perform the following steps:

1. Log on to the Windows Server 2008 R2 system with an account with administrator privileges.

2. Click Start, click All Programs, click Administrative Tools, and select Windows Server Backup.

3. In the Actions pane, select Recover to start the Recovery Wizard.

4. On the Getting Started page, select either to restore data previously backed up from the local computer or a different computer. For this example, select This Server (Servername), where Servername is the name of the server Windows Server Backup is connected to, and click Next to continue.

5. On the Select Backup Date page, select the correct date and time of the backup you will use to restore the data, and click Next to continue. Days with a successful backup are formatted in boldface.

6. On the Select Recovery Type page, select the Volumes option button, and click Next to continue.

7. On the Select Volumes page, the window displays each of the volumes contained in the backup that was previously chosen. Check the box next to the desired volume that will be restored, and select the destination volume to which you will restore the backed up volume.

8. After clicking Next on the Select Volumes page, a window opens, requesting confirmation that the data on the volume(s) will be lost by the recovery process; click Yes to continue with the volume recovery process.

9. On the Confirmation page, review the selections. If everything looks correct, click the Recover button to start the volume recovery.

10. On the Recovery Progress page, the recovery status of the volume will be displayed. After the recovery completes, review the results and click Close if the recovery was successful; otherwise, select the Errors tab to review the errors.

11. If the volume recovery was successful, the only additional step that might be required is to reboot the system if the data on the volume is shared or used by any applications or services. Reboot as required.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Managing and Accessing Windows Server Backup Media

noreply@blogger.com (Computing Tech) — Mon, 02 Jan 2012 04:48:00 PST

Microsoft has completely changed the way backups and backup media are managed with the release of Windows Server 2008. In previous editions of Windows Server versions, the NT Backup utility could back up the entire system or just a set of folders and files. The backup could be stored on tapes or they could be stored in a single .bkf file that is saved on a local disk or on a network shared folder. Starting with Windows Server Backup for Windows Server 2008 and Windows Vista, backups can be taken of only the entire system or volumes but not of granular folders or files. With Windows Server 2008 R2, Windows Server Backup supports backing up individual files and folders, and exclusions can be added to backup jobs as well. Windows Server Backup can store backups on dedicated locally attached disks on a DVD disk or a set of disks, or the backup can be stored on a network shared folder.

Windows Server Backup can be configured to run a scheduled backup or a manual backup. Either can be run from the graphical user interface or the command-line utility, but the backup options, including where the backup can be stored and the recovery options available, are different.

Windows Server Backup Managed Disks
Windows Server Backup can be used to run a manual backup or it can be used to run a scheduled backup. Scheduled backups can be stored on locally attached disks that are dedicated to Windows Server Backup, a folder on a local volume, or a network shared folder. When a scheduled Windows Server Backup job is created, the administrator can define which locally attached disks, folder, or network share will be used to store the backups. During the creation of the scheduled job, if dedicated disks are selected, which is recommended, the allocated disks will each be repartitioned and reformatted. Windows Server Backup will stamp the disk volume to match the time and date the scheduled job is created. By default, this disk will only be available on the local system through the Windows Server Backup program.

A Windows Server Backup disk can have a drive letter added after the initial backup is created if the disk needs to be accessed from within the operating system, from across the network, or if the backup data needs to be copied to additional disks or network folders for offsite storage. Although adding a drive letter to a dedicated Windows Server Backup disk is not recommended, it might be the only way or the most efficient way to make the backup media available to an alternate system if the disk cannot be locally attached to the alternate system. Getting access to this backup data, however, might prove to be challenging from Windows Explorer and might need to be accessed through Windows Server Backup. Backups contained on a Windows Server Backup dedicated disk can be used to restore an entire system, an entire volume, or a set of specified files and folders.

DVD Media
When Windows Server 2008 R2 systems have a local DVD writer drive, which is highly recommended, backups of Windows volumes and the complete system can be stored on DVD media. Backups stored on DVD media will span several DVDs and can be used when data needs to be restored to offsite servers or systems in an isolated network. Backups stored on DVD media can only be used to restore the entire Windows system or entire volumes. Selective restore of files and folders cannot be performed using DVD backup media.

Network Shared Folders
When Windows Server Backup is configured to back up to a network shared folder, backup administrators need to consider a few things. First, the share and NTFS permissions should be configured so that only backup administrators and specific service accounts can access and read this data. Also, if this share contains data that will be replicated by a third-party provider, special permissions might need to be added to support this. Another very important point to note about network shared folders for Windows Server Backup is that only the most recent copy of the backup will be stored there because each backup overwrites the previous. This is unlike backup to dedicated disks, which can store multiple versions and copies of a Windows Server 2008 R2 system backup.

Source of Information : Sams - Windows Server 2008 R2 Unleashed

Virtualizing Microsoft SQL Server

noreply@blogger.com (Computing Tech) — Thu, 29 Dec 2011 09:09:00 PST

The SQL performance team has published a document related to the use of SQL 2008 in a Hyper-V environment. A few of the key items are listed in this section, but it is strongly suggested that you download and review this document in its entirety prior to implementing SQL in a Hyper-V environment. To download this SQL team’s document, go to http://download.microsoft.com/download/d/9/4/d948f981-926e-40fa-a026-5bfcf076d9b9/SQL2008inHyperV2008.docx.

Use a synthetic network adapter provided by the Hyper-V Integration tools instead of a legacy network adapter when configuring networking for the virtual machine.

Avoid emulated devices for SQL Server deployments when possible. These devices can result in significantly more CPU overhead when compared to synthetic devices. SQL Server is I/O intensive, so it is recommended that you use the pass-through disk option as opposed to the fixed-size Virtual Hard Disks (VHDs). Dynamic VHDs are not recommended for performance reasons.

In the SQL Team’s document, they used locally attached storage on the Hyper-V server. Many virtual hosts are connected to shared storage using Fiber Channel, iSCSI, or NFS. Selecting the proper storage connection will greatly impact the I/O performance of the virtual SQL Server.

Source of Information : Elsevier-Microsoft Virtualization Master Microsoft Server Desktop Application and Presentation

Virtualizing Microsoft exchange server

noreply@blogger.com (Computing Tech) — Mon, 26 Dec 2011 09:01:00 PST

Virtualizing Exchange has been a topic of great controversy ever since virtualization first came on the scene. In the early years of virtualization, it was recommended NOT to run Exchange in a virtual environment because of the limitations of the infant technology. Since then, virtualization has matured in a way that has removed many, if not all, of those limitations. Unfortunately, the recommendations of the past have remained as a worry in today’s discussions surrounding the partnership of virtualization and Exchange. The truth is Microsoft fully supports the virtualization of Microsoft Exchange today. As with any other environment, you must be sure that you configure your virtual platform to properly support Exchange, but there are no limitations within Microsoft’s Hyper-V technology that should cause any concern in your discussions to virtualize Exchange. There are some key items that Microsoft has called out that IS professionals should be aware of when designing their virtual Exchange environments.

- The software platform should be Windows Server 2008, or any thirdparty vendor virtualization platform that has been validated by Microsoft’s Windows Server Virtualization Validation Program. Located here: www.windowsservercatalog.com/svvp.aspx?svvppage¼svvp.htm, the Validation Program includes some of the most well-known vendors of both hardware and software. The site will help you to identify those who have been validated by Microsoft to provide platforms capable of running all flavors of the Microsoft Servers.

- If you are planning to virtualize your Exchange environment, you must use Exchange Server 2007 with Service Pack 1 or later. Earlier, Exchange versions are not fully supported on a virtual platform. The use of the Unified Messaging role is not supported if your Exchange server is running within a virtual platform. It is important to note that the base Exchange 2007 system requirements WITHOUT the use of virtualization is Windows 2003, but the use of this operating system as a host for Exchange 2007 is not supported in the virtualization world. We mention this because some may consider building Exchange 2007 in a nonvirtual environment with the plan to migrate the complete operating system into Hyper-V at a later date. If you plan to do this, you must build your environment using Windows 2008 or later.

- Exchange 2007 on a virtual platform supports all of the most common forms of storage. These include virtual hard drives (VHD), SCSI, and iSCSI storage. If you plan to use SCSI or iSCSI, you must configure it to be presented as block-level storage within the hardware virtualization software, and it must be dedicated to the Exchange guest machine. Exchange 2007 does not support the use of network attached storage, but if the storage is attached at the host level, the guest will see it as local storage. Should you plan to use SCSI or iSCSI in your virtual Exchange environment, Hyper-V only supports VHDs up to 2040 gigabytes (GB) in size, and virtual IDE drives up to 127 GB; plan accordingly.

- Microsoft supports the use of both cluster continuous replication (CCR) and single copy clusters (SCC) within Exchange running in a virtual environment so long as there are no hypervisor-based clustering or migration technologies in use. An example of these technologies would be Quick Migration for Hyper-V and VMotion for VMWare. Likewise, Microsoft does support the use of hypervisor clustering and migration so long as CCR and SCC are not in use within the Exchange environment.

- One of the biggest advantages of virtualization is the ability to take snapshots of your virtual environment as part of a backup or disaster recovery plan. In the Exchange world this can be problematic because this kind of technology is not “application aware.” This means the snapshot technology is not capable of taking into account the way the application actually uses and processes its data. Because of the way Exchange processes data, Microsoft does not support the use of any kind of snapshot technology with your virtual Exchange server. However, it should be noted that in the case of Exchange, the other benefits of virtualization tend to outweigh the inability to use snapshot technology.

- When you are configuring the virtual processors for your Exchange host, it is important to understand that Exchange running in a virtual environment does not support a ratio of greater than 2:1. Hypervisors provide the ability to share the logical processors of the host server to the guest machines. For example, a dual processor system using quad core processors contains a total of eight logical processors in the host. You may have some virtual servers that end up using less processor power than another, so the full processor may not be needed by that server. Depending on the virtual servers, this may allow you to have much more than eight virtual servers configured to have two processors each. However, in the Exchange world, Microsoft would not support the allocation of more than 16 virtual processors across all of the guest machines running on the server, or a total of four quad processor Exchange servers.

Source of Information : Elsevier-Microsoft Virtualization Master Microsoft Server Desktop Application and Presentation

Static versus Dynamic Languages

noreply@blogger.com (Computing Tech) — Fri, 23 Dec 2011 07:47:00 PST

One of the great debates among programmers is about static versus dynamic languages. It’s a debate that will go on forever because both sides have good points. The basic difference has to do with when errors are detected. In a dynamic language, errors aren’t caught until the bad code is executed. For example, in a dynamic language like Python, if you write a method call like x.foo(), and x doesn’t have a “foo” method, you won’t get an error message until that statement actually executes. In a static language, you need to declare types for things. Then, using the information provided by those declarations, errors like the undefined method in the example above can be caught at compile time.

It’s a trade-off: in dynamic languages, you don’t need to write type declarations to prove to the compiler that your program is correct. That’s very convenient, and it can lead to a style of programming in which your code is much simpler—and simpler code is less likely to have hard-to-find errors.

On the other hand, static languages catch a lot of mistakes for you. They force you to be more rigorous about how you write your code in order to make sure that it passes the compiler, and that process causes you to produce better-designed code.

Personally, I fall on the static language side of things. I find that the extra work of dealing with the type system saves me a huge amount of effort in the long run. Most of the silly mistakes that I make get caught by the compiler and never cause problems at runtime. In fact, my own preference is for very strongly typed languages, like the functional language ML. ML’s type system is incredibly expressive and incredibly strict, much more so than more familiar static languages like Java and C++. But in return, my ML programs almost never have runtime errors. Nearly all of the mistakes that I make end up getting reflected as inconsistencies in types. I’ve written thousand-line programs in ML and had them work without a single error on the first run after spending days working with the compiler to get rid of the statically detected type errors.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

HTTP Status Codes

noreply@blogger.com (Computing Tech) — Wed, 14 Dec 2011 07:06:00 PST

The HTTP standard has an extensive list of status codes for server result messages. These are the ones you’ll encounter the most:

200 OK. The request was completed successfully. The body of the message will contain the result of the successful request.

301 Moved permanently. The requested has been permanently moved, and this and all future requests for the resource should be sent to the new location.

303 See other. For this request, the result can be found by doing a GET on a different URL. The URL can be found in the Location header of the message. This is generally used for the result of PUT requests, where after the PUT was successfully processed, the server tells the client where to look to see the result of the operation.

401 Unauthorized. The request was valid, but the user has not provided any authentication data to show that he or she should be permitted to see the resource. The user could use some other request to get an authentication code and then retry the request.

403 Forbidden. The request was valid, but the user is not allowed to access the specified resource. This is similar to 401 but indicates that either the user has been authenticated and still can’t access the resource or that even if the user was authenticated, that user is not permitted to access it.

404 Not found. No resource was found at the specified location.

500 Internal Server Error. Any error in the server during its processing of the request will end up generating a 500 error. In particular, for App Engine services that you implement, the client browser will receive a 500 when your request handlers crash and/or throw an exception.

501 Not implemented. The request wants to perform some operation that the server doesn’t support. You’ll see this most often if you do something like misspell the URL in a POST request.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

Why Start with Python?

noreply@blogger.com (Computing Tech) — Wed, 07 Dec 2011 18:58:00 PST

I’ll say more about this later, but I’m not a huge Python fan. We’r e starting with it first for a few reasons. First, Python is a very pleasant language that makes it possible to do a lot with a small amount of code. We can start writing Google App Engine programs with just a few lines of code. There’s very little in the way of required infrastructure. When you’re learning how to develop for the cloud, Python is great way to start.

Second, my tastes shouldn’t dictate how you should build your application. Python is a very powerful, flexible language, and it’s got excellent support in Google App Engine. If you’re a Python aficionado, then after reading this book, you should be able to build your App Engine applications in Python.

Third, we’re going to learn tools like GWT, which generate a lot of code for us, taking care of the underlying mechanisms of the client/server interaction in our cloud applications. For developing complicated applications, that saves us incredible amounts of effort. But it’s important to understand what’s happening behind the scenes.

Python gives us a good way of exploring the primitive infrastructure of a cloud application. We’ll be able to look at each piece of technology, build it up, and learn about how it works. When we get to GWT, it will be easy to understand what’s really going on.

If you decide you like doing your cloud programming in Python, you’ll learn enough to be able to do it. But even if you never write a cloud app using Python, taking the time to explore the basic technologies of cloud applications using Python will help you understand and debug your real applications in whatever language you decide to use.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

Cloud Computing Programming Systems

noreply@blogger.com (Computing Tech) — Tue, 29 Nov 2011 18:35:00 PST

There are multiple ways of programming the cloud. Before we start actually writing programs, we’ll take a quick look at a few examples to give you a sense of what sorts of options are available.

Amazon EC2
Amazon provides a variety of cloud-based services. Their main programming tool is called EC2, Elastic Computing Cloud.

EC2 is really a family of related services. Compared to App Engine, which provides a single, narrowly focused suite of APIs, EC2 is completely agnostic about programming APIs. It provides hundreds of different environments: you can run your application in EC2 using Linux, Solaris, or Windows Server; you can store data using DB2, Informix, MySQL, SQL Server, or Oracle; you can implement your code in Perl, Python, Ruby, Java, C++, or C#; you can run it using IBM’s Web Sphere or sMash, Apache JBoss, Oracle Web Logic, or Microsoft IIS. Depending on which combination you prefer and how much of each kind of resource (storage, CPU, network bandwidth) you plan to use, the costs vary from $0.10 per CPU hour and $0.10 per gigabyte of bandwidth to around $0.74 per CPU hour for high-end instances.

Amazon S3
Amazon provides another extremely interesting cloud service, which is very different from most other cloud offerings. S3, Simple Storage Service, is a pure storage system. It doesn’t provide the ability to run programs; it doesn’t provide any file system; it doesn’t provide any indexing. It’s pure block storage: you can allocate a chunk of storage that has a unique identifier, and then you can read and write bytes from that chunk using its identifier.

A variety of systems have been created that use S3 for storage: web based file systems, native OS file systems, database systems, and table storage systems. It’s a wonderful example of the cloud’s resource-based paradigm: the computation involved in storage is completely separated from the actual data storage itself. When you need storage, you buy a bunch of bytes of storage space from S3. When you need computation, you buy EC2 resources.

S3 is a really fascinating system. It’s very focused: it does exactly one thing and does it in an incredibly narrow way. But in an important sense, that’s exactly what the cloud is about. S3 is a perfectly focused service; it stores bytes for you.

S3 charges are based on two criteria: how much data you store and how much network bandwidth you use storing and retrieving your data. Amazon currently charges $0.15 per gigabyte per month and about $0.10 per gigabyte uploaded and $0.17 per gigabyte downloaded.

On a related note, Google provides a very similar cloud service, called Google Developer Storage, which replicates the basic features of S3 in the Google cloud.

IBM Computing on Demand
IBM provides a cloud service platform based on IBM’s suite of web service development that uses Web Sphere, DB2, and Lotus collaboration tools. The environment is the same as the IBM-based environment on EC2, but it runs in IBM’s data centers instead of Amazon’s.

Microsoft Azure
Microsoft has developed and deployed a cloud platform called Azure. Azure is a Windows-based platform that uses a combination of standard web services technologies (such as SOAP, REST, Servlets, and ASPs) and Microsoft’s proprietary APIs, like Silverlight. As a result, you get the ability to create extremely powerful applications that look

Very much like standard desktop applications. But the downside is it’s closely tied to the Windows platform, so the application clients run primarily on Windows. While there are Silverlight implementations for other platforms, the applications tend to only be reliable on Windows platforms and only fully functional in Internet Explorer.

So that’s the cloud. Now that we know what it is, we’re going to start learning about how to build applications in the cloud. Google has put together a really terrific platform, called App Engine, for you to build and run your own cloud applications.

In the rest of the book, we’re going to look in detail at the key pieces of building cloud-based web applications. We’ll start off working in Python. Python’s great for learning the basics: it lets you see what’s going on, and it makes it easy to quickly try different approaches and see what happens.

We’ll go through the full stack of techniques that you need for building a Google App Engine application in Python, starting with the basic building blocks: HTTP, services, and handlers. Then we’ll look at how you work with persistent data in the cloud using the App Engine data store service. And then, we’ll look at how to build user interfaces for your applications using HTTP, CSS, and AJAX.

From there, we’ll leave Python for a while and move into Java. In my opinion, Java can be a lot more convenient for building complex applications. Not that Python can’t or shouldn’t be used for advanced App Engine development, but my preference is to use Java. And App Engine provides access to an absolutely brilliant framework called GWT, which abstracts away most of the boilerplate plumbing of a web-based cloud application, allowing you to focus on the interesting parts. We’ll spend some time learning about how to build beautiful user interfaces using GWT and how to do AJAX-style communication using GWT’s remote procedure call service.

Finally, we’ll spend some time looking at the most complicated aspects of real web development. We’ll look at the details of how you can do sophisticated things using the App Engine data store service, how to implement server-side processing and computation using things like cron, and how to integrate security and authentication into your App Engine application.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

When to Develop for the Cloud

noreply@blogger.com (Computing Tech) — Mon, 21 Nov 2011 18:21:00 PST

So now you know what the cloud is. It’s a revolutionary way of thinking about computing; it’s a universe of servers that you can build an application on; it’s a world of services that you can build or that you can use to build other things. Now, the question is, when should you use it?

You can write almost any application you want in the cloud. In fact, many people strongly believe that everything should be in the cloud— that there’s no longer any reason to develop applications for standalone personal computers. I don’t go quite that far: many applications are well suited to the cloud, but that doesn’t mean that it’s the ideal platform for everything. You can build anything as a service in the cloud, but it might be a lot harder than developing it as a standalone application.

There are three kinds of applications that it makes sense to build in the cloud:

Collaborative applications.
If the application you’re building will be used by groups of people to work together, share data, communicate, or collaborate, then you really should build that application in the cloud. Collaboration is the cloud’s natural niche.

Services.
If you ask, “What does my application do?” and the most natural answer sounds like a service, then you’re looking at a cloud application. The difference between an application and a service can be subtle—you can describe almost anything as a service. The key question here is what’s the most natural description of it? If you want to describe the desktop iTunes application, you could say, “It lets people manage their music collections,” which does sound service-like. But it leaves out the key property of what the iTunes desktop application does: it manages a collection of music files on the users’ computers and lets them sync that music with their iPods using a serial cable. Described the latter way, it’s clear that it’s a desktop application, not a cloud application.

On the other hand, if you take a look at something like eMusic, you’ll come to a different conclusion. eMusic is a subscription based website that lets users browse an enormous collection of music and buy a certain number of songs per month. eMusic is clearly a service: it lets people search through a library of hundreds of thousands of musical tracks, providing them with the ability to listen to snippets, read reviews, comment on things that they’ve listened to, get suggestions for new things based on what they like, and ultimately select things to purchase. That’s clearly a service, and it makes sense to keep it in the cloud.

Large Computations.
Is your application intended to perform a massive computation, which you could never afford to do if you needed to buy your own computers to run it? If so, the cloud allows you to purchase time on a server farm of computers in an affordable way and run your application. This is great for people like genetics researchers, who need to run massive computations but don’t have the money or other resources to set up a dedicated data center for their computations. Instead, they can purchase time on commercial data centers, which they share with many other users.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

Cloud versus Client-Server

noreply@blogger.com (Computing Tech) — Wed, 16 Nov 2011 05:52:00 PST

In many ways, the basic style of development for cloud-based software is similar to programming for client-server computing. Both are based on the idea that you don’t really run programs on your own computer. Your computer provides a window into an application, but it doesn’t run the application itself. Instead of running the program on your computer, all you do on your own computer is run some kind of user interface. The real program is running somewhere else on a computer called a server. You use the server because, for whatever reason, the resources necessary to run the program aren’t available on your local computer: it’s cheaper, faster, or more convenient to run the program somewhere else where the necessary resources are easy to obtain.

The big difference between cloud and client-server development is in what you know: in traditional client-server systems, you might have a specific computer that is your server, and that’s where your stuff is running. The computer may not be sitting on your desk in front of you, but you know where it is. For example, when I was in college, one of the first big computers I used was a VAX 11/780 nicknamed “Gold.” Gold lived in the Rutgers university computing lab in Hill Center. I used Gold pretty much daily for at least a year before I actually got to see it. The data center had at least thirty other computers: several DEC 20s, a couple of Pyramids, an S/390, and a bunch of Suns. But of those machines, I specifically used Gold. Every program that I wrote, I wrote specifically to run on Gold, and that’s the only place that I could run it.

In the cloud, you aren’t confined to a specific server. You have computing resources—that is, someone is renting you a certain amount of computation on some collection of computers somewhere. You don’t know where they are; you don’t know what kind of computers they are. You could have two massive machines with 32 processors each and 64 gigabytes of memory; or they could be 64 dinky little single-processor machines with 2 gigabytes of memory. The computers where you run your program could have great big disks of their own, or they could be diskless machines accessing storage on dedicated storage servers. To you, as a user of the cloud, that doesn’t matter. You’ ve got the resources you pay for, and where they are makes no difference as long as you get what you need.

Source of Information on: Pragmatic - Code in the Cloud Programming Google App Engine 2011

Cloud to the Developer

noreply@blogger.com (Computing Tech) — Tue, 08 Nov 2011 17:35:00 PST

Cloud computing is a fundamental change from how computers and software have worked in the past. Traditionally, if you wanted to run an application, you went out and bought a computer and software, set it up on your own premises, and ran your program. You needed to pick out which operating system you were going to run, handle the installation of your software, and maintain your computer—keeping track of software upgrades, security, backups, and so on.

With cloud computing, you don’t do any of that. If you’re a user of the cloud, you buy access to the application you want and then connect to it from anywhere. Installing the software, maintaining the hardware and software where the application runs, making sure that the data is kept safe and secure—none of that is your concern. In the cloud, you buy software as a service. If you need more storage than a typical user, you buy extra storage from the service provider. If that means buying and installing a new disk drive, that’s up to the provider. You just buy storage-as-a-service from them: how they provide it is their problem. You tell them what you need—in both the physical sense (“I need 1TB of storage.”) and in less tangible quality-of-service senses (“I need to guarantee that my storage is transactional, so that after I commit a change, data will never be lost.”). You tell them your requirements, and some cloud provider will sell you a service that meets those requirements.

What this means is that when you’re developing for the cloud, instead of buying a computer and running software on it, you break things down to basic building blocks, buy those pieces from service providers, and put them together however you want to build a system.

The building blocks are the resources you need to run a program or to perform a task. Resources include things like processing time, network bandwidth, disk storage, and memory. As a user of the cloud, you don’t need to be concerned about where these resources are located. You know what you need, and you buy that from whoever can provide it to you most conveniently.

For developers, cloud computing introduces an even bigger change. When you develop for the cloud, you’re not building a piece of software to sell to your customers—you’re building a service for your customers to use. Understanding that difference is crucial: you need to design your application around the idea that it’s a service you’re going to provide to users, not a standalone application that they’re going to install on their computers. Your customers are going to choose a service based on the tasks they want to accomplish, so your application needs to be designed with the task in mind, and you must provide it in the most flexible way possible.

For example, if you want to build a to-do list application for a desktop computer, it’s a fairly straightforward process. There are lots of variations in how you can arrange the UI, but the basic idea of what you’re building is obvious. You would build one UI—after all, why would you need more than one? And you’d build it mainly for a single user. If you are developing this to-do list application for the cloud, though, you’d want multiple UIs: at the very least, you’d want one UI for people accessing your service using their desktop computer and one for people using a mobile browser on a cell phone. You’ d probably want to provide an open interface that other people could use for building clients for other devices. And you’d need to design it for multiple users; if you put an application in the cloud, there’s only one program, but it can be used by lots of people. So you need to design it around the assumption that even if users never work together using your application, it’s still a multi-user system.

For developers, the most exciting aspect of cloud computing is its scalability. When you’re developing in the cloud, you can write a simple program to be used by one or two people—and then, without ever changing a line of code, that program can scale up to support millions of users. The program is scale-neutral: you write it so it will work equally well for one dozen users or one million users. As you get more users, all you need to do is buy more resources—and your program will just work. You can start with a simple program running on one server somewhere in the cloud and scale up by adding resources until you’ve got millions of users.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

The Cloud Concept

noreply@blogger.com (Computing Tech) — Thu, 03 Nov 2011 08:22:58 PDT

In the modern world of the Internet and the World Wide Web, there are thousands upon thousands of computers sitting in data centers, scattered around the world. We use those computers constantly—for chatting with other people, sending email, playing games, and reading and writing blogs. When we’re doing one of these everyday activities, we’re accessing a program running on a server, using our browser as a client.

But where is the program actually running? Where is the data? Where are the servers? They’re somewhere out there, somewhere in some data center, somewhere in the world. You don’t know where, and more importantly, you don’t care; there’s absolutely no reason for you to care. What matters to you is that you can get to the program and the datavwhenever you need to.

Let’s look at a simple example. A few years ago, I started writing a blog.v(The blog has since moved, but it’s still a good example.) When I gotvstarted, I used Google’s Blogger service to write it. Every day, I wouldvopen up my web browser, go to http://goodmath.blogspot.com/admin, andvstart writing. When I finished, I’d click on the Post button, and the blogvpost would appear to all of my readers. From my point of view, it justvworked. All I needed was my web browser and the URL, and I could write my blog.

Behind the scenes, Blogger is a complex piece of software run by Google in one of its data centers. It hosts hundreds of thousands of blogs, and those blogs are read by millions of users every day. When you look at it this way, it’s obvious that the software behind Blogger is running on lots of computers. How many? We don’t know. In fact, it’s probably not even a fixed number—when not many people are accessing it, it doesn’t need to be running on as many machines; when more people start using it, it needs more machines. The number of machines running it varies. But from the user’s point of view—whether that user is a blog author or a blog reader—none of that matters. Blogger is a service, and it works. When I want to write a post, I can go to Blogger and write it, and when people go to my blog’s web page, they can read it.

That’s the fundamental idea of the cloud: programs and data are on a computer somewhere out there, and you neither know nor care where that computer is.

Why call this collection of resources a cloud? A cloud is a huge collection of tiny droplets of water. Some of those droplets fall on my yard, providing the trees and the lawn with water; some run off into the reservoir from which my drinking water comes. And the clouds themselves grow from evaporated water, which comes from all over the place. All I want is enough water in my yard to keep the plants alive and enough in the reservoir so that I have something to drink. I don’t care which cloud brings the rain; it’s all the same to me. I don’t care where on earth that water came from. It’s all just water—the particular drops are pretty much exactly the same, and I can’t tell the difference. As long as I get enough, I’m happy.

So think about the various data centers around the world where companies have swarms of computers—as clouds. Lots of the biggest players in network computing, including Google, Amazon, Microsoft, IBM, and Yahoo, all have thousands of machines connected to networks running all sorts of software. Each of those centers is a cloud, and each processor, each disk drive, is a droplet of water in that cloud. In the cloud world, when you write a program, you don’t know what computer it’s going to run on. You don’t know where the disks that store the data are, and you don’t need to care. You just need to know how many droplets you need.

Source of Information : Pragmatic - Code in the Cloud Programming Google App Engine 2011

The Story of RAID

noreply@blogger.com (Computing Tech) — Wed, 07 Sep 2011 10:20:00 PDT

If you’ve got only one hard drive in your server, feel free to skip ahead. Otherwise, let’s talk about putting those extra drives to use. The acronym RAID stands for redundant array of inexpensive disks, although if you’re a businessperson, you can substitute the word independent for inexpensive. We forgive you. And if you’re in France, RAID is short for recherche assistance intervention dissuasion, which is an elite commando unit of the National Police—but if that’s the RAID you need help with, you’re reading the wrong book. We think RAID is just a really awesome idea for data: When dealing with your information, it provides extra speed, fault tolerance, or both.

At its core, RAID is just a way to replicate the same information across multiple physical drives. The process can be set up in a number of ways, and specific kinds of drive configurations are referred to as RAID levels. These days, even low- to mid-range servers ship with integrated hardware RAID controllers, which operate without any support from the OS. If your new server doesn’t come with a RAID controller, you can use the software RAID functionality in the Ubuntu kernel to accomplish the same goal.

Setting up software RAID while installing your Linux system was difficult and unwieldy only a short while ago, but it is a breeze these days: The Ubuntu installer provides a nice, convenient interface for it and then handles all the requisite backstage magic. You can choose from three RAID levels: 0, 1, and 5.

RAID 0 A so-called striped set, RAID 0 allows you to pool the storage space of a number of separate drives into one large, virtual drive. The important thing to keep in mind is that RAID 0 does not actually concatenate the physical drives—it actually spreads the data across them evenly, which means that no more space will be used on each physical drive than can fit on the smallest one. In practical terms, if you had two 250GB drives and a 200GB drive, the total amount of space on your virtual drive would equal 600GB; 50GB on each of the two larger drives would go unused. Spreading data in this fashion provides amazing performance but also significantly decreases reliability. If any of the drives in your RAID 0 array fail, the entire array will come crashing down, taking your data with it.

RAID 1 This level provides very straightforward data replication. It will take the contents of one physical drive and multiplex it to as many other drives as you’d like. A RAID 1 array does not grow in size with the addition of extra drives—instead, it grows in reliability and read performance. The size of the entire array is limited by the size of its smallest constituent drive.

RAID 5 When the chief goal of your storage is fault tolerance, and you want to use more space than provided by the single physical drive in RAID 1, this is the level you want to use. RAID 5 lets you use n identically sized physical drives (if different-sized drives are present, no more space than the size of the smallest one will be used on each drive) to construct an array whose total available space is that of n–1 drives, and the array tolerates the failure of any one—but no more than one—drive without data loss.

Which RAID to Choose? If you’re indecisive by nature, the past few paragraphs may have left you awkwardly hunched in your chair, mercilessly chewing a No. 2 pencil, feet tapping the floor nervously. Luckily, the initial choice of RAID level is often a no-brainer, so you’ll have to direct your indecision elsewhere. If you have one hard drive, no RAID for you. Do not pass Go, do not collect $200. Two drives? Toss them into RAID 1, and sleep better at night. Three or more? RAID 5. Unless you really know what you’re doing, avoid RAID 0 like the plague. If you’re not serving mostly read-only data without a care about redundancy, RAID 0 isn’t what you want.

The Mythical Parity Drive
If you toss five 200GB drives into a RAID 5 array, the array’s total usable size will be 800GB, or that of four drives. This makes it easy to mistakenly believe that a RAID 5 array “sacrifices” one of the drives for maintaining redundancy and parity, but this is not the case. Through some neat mathematics of polynomial coefficients over Galois fields, the actual parity information is striped across all drives equally, allowing any single drive to fail without compromising the data. Don’t worry, though. We won’t quiz you on the math.

Other RAID Modes
Though the installer offers only the most common RAID modes—0, 1, and 5—many other RAID modes exist and can be configured after the installation. Take a look at http://en.wikipedia.org/wiki/RAID for a detailed explanation of all the modes.

Source of Information : Prentice Hall The official Ubuntu Book 5th Edition 2010

What Is Ubuntu Server?

noreply@blogger.com (Computing Tech) — Sun, 04 Sep 2011 10:13:00 PDT

By far the most common reaction from users first encountering Ubuntu Server is one of utter and hopeless confusion. People are foggy on whether Ubuntu Server is a whole new distribution or an Ubuntu derivative like Kubuntu (only for servers) or perhaps something else entirely.

Let’s clear things up a bit. The primary software store for Ubuntu and official derivatives is called the Ubuntu archive. The archive is merely a collection of software packages in Debian “deb” format, and it contains every single package that makes up distributions such as Ubuntu, Edubuntu, Xubuntu, Kubuntu, and Ubuntu Server. What makes Kubuntu separate from Ubuntu, then, is only the set of packages from the archive that its installer installs by default and that its CDs carry.

Ubuntu Server is no different. It depends on the very same archive as the standard Ubuntu distribution, but it installs a distinctive set of default packages. Notably, the set of packages comprising Ubuntu Server is very small. The installer will not install things such as a graphical environment or many user programs by default. But since all the packages for Ubuntu Server come from the same official Ubuntu archive, you can install any package you like later. In theory, there’s nothing stopping you from transforming an Ubuntu Server install into a regular Ubuntu desktop installation or vice versa (in practice, this is tricky, and we don’t recommend you try it). You can even go from running Kubuntu to running Ubuntu Server. The archive paradigm gives you maximum flexibility.

We’ve established that Ubuntu Server just provides a different set of default packages than Ubuntu. But what’s important about that different set? What makes Ubuntu Server a server platform?

The most significant difference is a custom server kernel. This kernel employs an internal timer frequency of 100Hz instead of the desktop default of 250Hz, uses the deadline I/O scheduler instead of the desktop’s CFQ scheduler, and contains a batch of other minor tweaks for virtualization, memory support, and routing. We’ll spare you the OS theory: The idea is to offer some extra performance and throughput for server applications. In addition, the server kernel supports basic NUMA, a memory design used in some multiprocessor systems that can dramatically increase multiprocessing performance.

So what else is different in Ubuntu Server? Other than the server kernel and a minimal set of packages, not too much. Though Ubuntu has supported a minimal installation mode for a number of releases, spinning off Ubuntu Server into a separate product that truly stands on its own is still a young effort, but one that’s moving along very quickly.

Starting with Ubuntu Server 6.06 LTS, known as Dapper Drake, Ubuntu Server offers officially supported packages for the Red Hat Cluster Suite, Red Hat’s Global File System (GFS), Oracle’s OCFS2 filesystem, and the Linux Virtual Server utilities: keepalived and ipvsadm. Combined with the specialized server kernel, these bits already let you use your Ubuntu Server for some heavy lifting. And there’s a growing lineup of compelling features, including built-in virtualization, interoperability with Windows machines on the network through Samba, automatic version control for configuration files, support for LDAP directory services, hard drive replication over the network, and even a healthy dose of the latest buzzword— cloud computing.

Source of Information : Prentice Hall The official Ubuntu Book 5th Edition 2010

Surfing the Web

noreply@blogger.com (Computing Tech) — Tue, 30 Aug 2011 10:45:00 PDT

Browsers have actually been around for a long time, but were never really called browsers. Instead, they were called text readers or read-only applications, because what these programs did was open simple files of text and let someone read them—like a book. These programs were on computers called dumb terminals.

It seems odd to call a computer dumb, but compared to the computers used today, these computers weren’t very smart. All they did was display information from big, monster servers called mainframes that were the size of an average living room. These servers weren’t all that smart, either, but they were good enough to take a lot of information and help businesspeople and scientists make sense of it.

The problem was that all these dumb terminals could only talk to the servers they were connected to. There was an Internet back then, but there was no World Wide Web; Internet traffic was mainly limited to messaging and file transfers, using tools such as Usenet, Archie, or Gopher.

Then, in 1990, a scientist in Switzerland, Sir Tim Berners-Lee, got a brilliant idea. What if you could read files on any computer connected to the Internet any time you wanted? You could put those files on a special server that had one job—showing those files to anyone who asked for them. Sir Berners-Lee, who was knighted for his work at the CERN institute, knew this idea would only work if all of these files were made readable by any computer. File compatibility was (and still can be) a huge obstacle for users to overcome.

So, Sir Berners-Lee suggested that people use HyperText Markup Language (HTML) files. Because they are essentially ASCII text files, HTML files could be read by any computer, would let people create any content they wanted, and would have hyperlinks—something that would revolutionize the way people absorbed material.

Browsers came about as instruments to read all of these new HTML files. As with the dumb terminals, Sir Berners-Lee just wanted people to read information quickly in files—not to change their content. So he and his colleagues figured out a way to make a program that did nothing but read and display HTML. Other people got involved and made the application read more complicated HTML code.

People began reading the information on the Web page and calling the process of reading those pages browsing—and that’s where the browser name comes from. Later, when the general public started using the Web, the verb browsing got morphed into surfing. The name browser stuck, though, because it still more accurately describes what this type of application does. You can call any program like this a browser, of course. A program that does nothing but show pictures could be a picture browser. But these days the name is more synonymous with Web browsers, such as the most famous open-source browser today: Firefox.

Source of Information : Cengage-Introducing Fedora 2010

Introducing Firefox

noreply@blogger.com (Computing Tech) — Fri, 26 Aug 2011 10:38:00 PDT

In the olden days of the Internet (all of 17 years ago), life was uncomplicated. The simple concept of hyperlinks on a text page was just emerging. Some links went to other pages; others went to files to be downloaded—perhaps a picture or two. Browsers such as Lynx only had to contend with text—life was good.

In 1993, everything changed forever. The National Center for Supercomputing Applications (NCSA) at the University of Illinois created Mosaic—a browser capable of displaying text and pictures. Suddenly, users could see illustrated Web pages, which facilitated the flow of information. A year later, one of the Mosaic developers left NCSA and launched his own browser—Netscape Navigator 1.1.

Since then, the capability of browsers has grown even more in response to more complex content. Need to hear a sound file? The browser will take care of it. Need to view a Flash animation? Not only will a browser display it for you, but the browser can also automatically go get the required viewer if you don’t already have it.

These sophisticated features are a long way from the early Internet days, that’s for sure.

One of the direct descendants of that early Netscape browser is Firefox, a crossplatform open-source browser that has taken the desktop world by storm, no matter what the platform. Even on Windows, traditionally the bailiwick of Internet Explorer, Firefox has a 10+ percent browser share, which may not seem like a lot, except when you consider it’s only been around for a couple of years.

What makes Firefox special is its speed, stability, and security. Unlike Internet Explorer, which is tied closely to the Windows operating system on a code level, Firefox is a separate application. So, even if someone can figure out how to maliciously hack Firefox, it won’t damage anything beyond the browser. When Internet Explorer is hacked, all of Windows can become vulnerable.

Another unique feature of Firefox is the available extensions. Because Firefox is open, developers can create small add-on programs that can handle a variety of tasks, like displaying newsfeeds, synchronizing a user’s settings with any Firefox browser they use, blocking advertising . . . it’s a long list.

Finally, something that Firefox has had for quite some time, before Internet Explorer picked it up, is a tabbed interface. Tabs let you display multiple pages in a single window, a very useful feature for power surfers.

Source of Information : Cengage-Introducing Fedora 2010

Fedora Software Repositories

noreply@blogger.com (Computing Tech) — Mon, 22 Aug 2011 10:30:01 PDT

One of the brilliant features of Fedora is that it only comes on one CD disc. Not every operating system can brag about that. Indeed, many Linux distributions are delivered to users through multiple disks.

Formerly, the strategy in delivering a Linux distribution to your home or office was not very complex: all of the applications a user needed or would ever need in the future would be delivered on one complete set of CDs (or, later, one or two DVDs). The advantage here was that once you downloaded and burned all of those CDs, you would be all set to run that distribution without having to download additional software later. But the average CD image download, discussed. That’s a lot of data, even for today’s broadband connections. Having to do this for three, five, or even seven CDs is a very time-consuming undertaking for most users, unless they are willing to pay to have those same CDs delivered by mail.

Fedora flips the model around a bit. Working with the knowledge that a majority of Internet users now have broadband access, the Fedora Project has decided to send out just the absolutely necessary Fedora applications on one CD and leave the rest online on servers scattered around the world for users to download as needed.

This may seem inefficient, since you must have Internet access of some kind to make this work. But consider that most operating systems update themselves via Internet anyway, so in order to keep Fedora up to date, online access was needed anyway. And only downloading and burning one CD is a lot faster than downloading and burning CDs plural. Delivering a ‘‘core’’ distribution also gives users much greater flexibility in picking and choosing what software applications they want on their system. It also means their hard drives won’t be loaded with stuff they don’t need.

To give you an idea of just how much more software is available, consider these numbers: a standard installation of Fedora has around 1,100 packages. Currently, there are over 12,000 total application packages available.

Fedora, like its sibling Red Hat Enterprise Linux, organizes its software in repositories. There are three primary repositories for Fedora, each holding a specific class of software. Let’s walk through them now.

The three official Fedora repositories are pretty clearly named, but let’s examine them anyway.
» Fedora. This repository holds all of Fedora’s officially supported software. Everything that Fedora must have to actually run is in here, and all of the software is under a free software license. Additional applications in this repository include AbiWord, Evolution, Firefox, Gaim, OpenOffice.org, and Thunderbird.

» Updates. This repository contains any software that has been updated because of a bug or security fix.

» Source. All of the source code packages for Fedora software are found in this repository.

Adding Repositories
These are not the only repositories that Fedora can use. There aremany communityrun repositories on the Internet for Fedora, each holding specialized software that the Fedora Project does not want to host.

There are many software applications out there that can run on Linux, but because their licenses are completely proprietary, some Linux distributions won’t touch them with a 10-foot pole. By virtue of its Linux origins, Fedora’s makers feel obligated to abide by this philosophy, keeping totally commercial packages away from Fedora.

But there is an important distinction here. While the Fedora Project does not release commercial software with Fedora, that does not preclude letting users have access to a commercial repository after they have downloaded and installed

Fedora. A fine distinction, to be sure, but it gives users the advantage of making their own choices about what software they want to use. All of the package managers in Fedora work off a master list of repositories stored on your PC. From this file, known as sources.list, the package managers know which repositories to check for new software and if there are any updates available for software installed on your system. If you want these managers to peruse another repository, you will need to modify sources.list with the new information.

Fedora users in the know are aware of three such third-party repositories that will get you access to the latest in cutting-edge software for Fedora. These are the Dribble, Freshrpms, and rpm.livna.org repositories. Fortunately, you won’t have to add these repositories one at a time. Instead, you can use one command to add RPM Fusion to your sources.list, which will accomplish the same thing.

This operation will be done using a command-line application. Command-line applications are always run in a Terminal window, one of the plainest and most versatile tools found in Fedora. To start Terminal, click on the Applications | System Tools | Terminal menu command

Source of Information : Cengage-Introducing Fedora 2010