]-[3ny0 ONLINE

Safely Rebooting a Hanging Server

noreply@blogger.com (Jessie Evangelista) — Sun, 29 Apr 2012 18:44:45 PDT

When all else fails, go to the physical server console and hit:
Alt-SysRq R (wait for 21 secs)
Alt-SysRq E (wait for 21 secs)
Alt-SysRq I (wait for 21 secs)
Alt-SysRq S (wait for 21 secs)
Alt-SysRq U (wait for 21 secs)
Alt-SysRq B

Then cross your fingers as the server should reboot

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Mirroring the grails documentation with wget

noreply@blogger.com (Jessie Evangelista) — Tue, 17 Apr 2012 08:03:42 PDT

I will be offline most of the time in the next couple of days so I had to have a copy of the latest Grails 2.0.3 documentation available locally for browsing. Here is how I made one:

wget \
--recursive \
--convert-links \
--page-requisites \
--domains grails.org \
--no-parent \
--no-clobber \
--exclude-directories="doc/2.0.3/api/" \
http://grails.org/doc/2.0.3/

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Problem with grails, maven and spring security

noreply@blogger.com (Jessie Evangelista) — Fri, 13 Apr 2012 17:28:01 PDT

Environment:
Ubuntu 12.04 3.2.0-20-generic-pae kernel
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-3ubuntu3)
OpenJDK Server VM (build 20.0-b12, mixed mode)

I installed STS 2.9.1 RELEASE which includes apache-maven-3.0.3

I placed the apache-maven-3.0.3 in my PATH environment variable

I created a project with:
mvn archetype:generate \
-DarchetypeGroupId=org.grails \
-DarchetypeArtifactId=grails-maven-archetype \
-DarchetypeVersion=1.3.7 \
-Dversion=1.0.0alpha \
-DgroupId=com.henyo.foobar -DartifactId=foobar

mvn proceeded to download the internet and then created the project folder with the pom file
I modified the pom file to set the source and target to 1.6 as described in the grails manual

I then did:
mvn initialize
which created the grails directory structure

I tried:
mvn grails:run-app
which resulted in the app successfully running

I then tried running just the unit tests with:
mvn grails:exec -Dcommand=test-app -Dargs="--unit"
which resulted in successful build

I then installed the spring security core plugin with:
mvn grails:install-plugin -DpluginName=spring-securit-core

I then tried using the s2-quickstart script:
mvn grails:exec -Dcommand=s2-quickstart -Dargs="com.henyo.foobar.model User Role"
which resulted in a build FAILURE:
[ERROR] Failed to execute goal org.grails:grails-maven-plugin:1.3.7:exec (default-cli) on project foobar: Unable to start Grails: java.lang.reflect.InvocationTargetException: org/springframework/security/core/Authentication: org.springframework.security.core.Authentication -> [Help 1]

It seems that the grails maven integration still needs a lot of work. I suspect this is a dependency resolution issue.

Uploaded a sample project that has this issue: http://dl.dropbox.com/u/5541070/foobar.tar.gz

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Books for Software Development

noreply@blogger.com (Jessie Evangelista) — Fri, 13 Apr 2012 08:45:14 PDT

My updated reading list

Learning Programming
-------------
How to think like a computer scientist: Python Edition
Thinking in C beta 3
The Passionate Programmer

Learning Java
-------------
How to think like a computer scientist: Java Edition
Objects First with Java
Head First Java 2nd Ed
Thinking in Java 4th Ed
Big Java
Agile Java: Crafting Code with Test-Driven Development
Core Java Vol 1 & 2
The Art & Science of Java
The Java Programming Language

Programming Practices
---------------------
The Pragmatic Programmer: From Journeyman to Master
Pragmatic Version control using git
Pragmatic Unit testing in Java with JUnit
Pragmatic Project Automation
Debug It
Ship it
Release it

Learning Basic Web Frontend Development
---------------------------------------
Head First HTML with CSS & XHTML
Head First Javascript
Javascript the Good Parts
Stylin' with CSS: A Designer's Guide (2nd Edition)
Designing with Web Standards by Jeffrey Zeldman and Ethan Marcotte
Web Design for Developers: A Programmer's Guide to Design Tools and Techniques by Brian P. Hogan
Eric Meyer on CSS: Mastering the Language of Web Design by Eric Meyer
JQuery in Action by Bear Bibeault and Yehuda Katz
Handcrafted CSS by Dan Cederholm with Ethan Marcotte

Learning Swing Frontend Development
-----------------------------------
Desktop Java Live
Swing Second Edition
Java Swing

Mastering Software Development
------------------------------
Head First Object-Oriented Analysis and Design
Program Development in Java
The Elements of Java(TM) Style
Effective Java
Practical Java
Code Complete: A practical handbook of Software Construction
Clean Code: A Handbook of Agile Software Craftsmanship
Head First Design Patterns
Design Patterns: Elements of Reusable Object-Oriented Software
Patterns of Enterprise Application Architecture
Domain-Driven Design
Refactoring: Improving the Design of Existing Code
Refactoring to Patterns
SQL Anti-patterns
Modular Java
Growing Object-Oriented Software Guided by Tests
Holub on Patterns:Learning Design Patterns by Looking at Code
Test Driven Development by Kent Beck
XUnit Test Patterns - Refactoring Test Code by Gerard Meszaros

Methodology and Management
--------------------------
UML Distilled, 2nd Edition
Extreme Programming Explained
The Unified Software Development Process
Rapid Development: Taming Wild Software Schedules
Peopleware: Productive Projects and Teams
The Mythical Man-Month
Software Runaways: Monumental Software Disasters
Software Creativity
Agile Estimating and Planning by Mike Cohn
Agile Software Development, Principles, Patterns, and Practices by Robert (Bob) C. Martin
Agile Retrospectives: Making Good Teams Great by Esther Derby, Diana Larsen, and Ken Schwaber
Succeeding with Agile: Software Development Using Scrum by Mike Cohn
Agile Testing: A Practical Guide for Testers and Agile Teams by Lisa Crispin and Janet Gregory
Extreme Programming Installed by Ron Jeffries, Ann Anderson, and Chet Hendrickson
Behind Closed Doors: Secrets of Great Management by Johanna Rothman, and Esther Derby
Leading Lean Software Development: Results Are Not the Point by Mary and Tom Poppendieck
Lean-Agile Software Development: Achieving Enterprise Agility by Alan Shalloway, Guy Beaver, and James R. Trott
The Art of Agile Development by James Shore and Shane Warden

Mastering Groovy and Grails
---------------------------
Groovy in Action
The Definitive Guide to Grails
Grails in Action
Groovy Recipes
Programming Groovy

Mastering Web Design
--------------------
Web Design for Developers
Head First Web Design
Designing Web Usability

Mastering User Interface Design
-------------------------------
User Interface Design for Programmers
Don't Make me Think
About Face: The Essentials of User Interface Design
Design of Everyday Things
The Non-Designer's Design Book

Mastering Hardcore Stuff
------------------------
Code: The Hidden Language of Computer Hardware and Software by Charles Petzold
The C Programming Language
Structure and Interpretation of Computer Programs
Introduction to Algorithms by CLRS (Cormen,Leiserson,Rivest,Stein)
Compilers: Principles, Techniques and Tools
Test Driven Development for Embedded C
The Art of Computer Programming

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Trying Ubuntu 12.04LTS Precise Pangolin

noreply@blogger.com (Jessie Evangelista) — Wed, 04 Apr 2012 08:06:02 PDT

I migrated my desktop from Ubuntu 10.04LTS to Ubuntu 12.04LTS.

A few things I needed to add after installation:

Chromium as my default browser
adobe-flash to be able to play flash games on facebook
openjdk-6-jdk for work stuff
icedtea-plugin to be able to run charting applet on citisec
pidgin for messaging
git for more work
smartgit for routine pushing and comitting to git repos
smartsvn for routine pushing and comitting to git repos
STS for work stuff
DB Visualizer for work stuff
Virtual Box for desktop virtualization
Dia for diagramming
synergy to share one keyboard between my desktop and laptop
dropbox for personal file sharing
pencil for mockups
smplayer for watching videos
vlc for videos that do not work with smplayer
git gui for simple git commits
myqsl-server for development work
mysql workbench for managing mysql database
postgresql for development work
pgadmin for managing postgres database

Should I be replacing stuff on the list with something else? What other stuff have I forgotten to install?

I hope you found the post useful. You can subscribe via email or subscribe via a feed reader to get relevant updates from this blog. Have a nice day.

Protecting ProxmoxVE VMs with IPCop on KVM

noreply@blogger.com (Jessie Evangelista) — Mon, 02 Apr 2012 07:35:37 PDT

I found out a few weeks ago that protecting openvz virtual machines running ubuntu was a bit problematic as I was unable to run UFW on them.

I was able to setup IPCop v2.04 on KVM which will act as a virtual firewall for all of the virtual machines in our ProxmoxVE 2.0 cluster

I hope you found the post useful. You can subscribe via email or subscribe via a feed reader to get relevant updates from this blog. Have a nice day.

Building a good Software Startup

noreply@blogger.com (Jessie Evangelista) — Thu, 29 Mar 2012 22:04:37 PDT

If I were to build a good software startup today, I'd run with the following ideas.

Hire only good people who get things DONE.
Even if they are more expensive in terms of compensation.
Quality trumps numbers. No doubt about it.

Development Team

1 Lead Developer
1 Senior Developer
2 Junior Developers
2 Business Analyst/QA

Operations Team

1 Lead Systems Admin
1 Senior System Admin
6 Junior System Admins

Give your team a quiet working environment with ergonomic furniture and equipment

Give your team good internet connection

the faster they can download their installers, the earlier they can start working on code
the faster they can look up the solution on google or stackoverflow, the faster they can proceed to the next problem

Give your team good computer hardware

at least dual core processors with virtualization support
at least 8GB memory
at least 2 hard drives for mirror setup
at least 2 screens

Make sure to have enough environments to test, deploy and support the system properly.

Development Environment
Staging Environment
Support Environment
Production Environment

Make use of Free or Open Source systems to manage the development process.
Buy a commercial product only if you can't find a solution that fits.

Project/Issue Tracking with Source Code Management Options:

Indefero
Gitorious
Gitlab
Redmine+gitolite

Continuous Integration Server Options:

Jenkins
Team City

Code Quality:

Sonar

Setup google apps for for email, calendar and other stuff

As an example, here is how I would set it up on three physical servers:

Server#1 running ProxmoxVE
- Firewall/Proxy Server/Package Cache(apt,yum,mvn) VM
- Redmine+gitolite VM
- Jenkins VM
- Sonar VM
- NFS/Samba Server VM

Server#2 running ProxmoxVE
- Development Environment VM
- Staging Environment VM
- Support Environment VM

Server#3 for storage of backups
- nexentastor or freenas or centos+zfsonlinux

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ProxmoxVE 2: Configuring DRBD

noreply@blogger.com (Jessie Evangelista) — Tue, 27 Mar 2012 23:43:48 PDT

I am running ProxmoxVE 2.0-35/d07f49c3 on two nodes connected using a cross cable on gigabit nics.
host1 ip: 10.0.10.201
host2 ip: 10.0.10.202

Check if drbd module is available

modprobe -l | grep drbd

Check if drbd module is loaded

lsmod | grep drbd

If not, load it with

modprobe -v drbd

Check the module version

modinfo drbd | grep version

I installed the appropriate drbd8-utils package on both nodes

dpkg -i drbd8-utils_8.3.10-0_amd64.deb

I built my own deb from source. You can find my build here.

I shrank the data volume on both of
I made use of the extents I freed up by shrinking the data volume to create an lvm volume that will be used for drbd.

lvcreate --verbose --extents 50000 --name lv4drbd pve

Next I modified /etc/drbd.d/global_common.conf so that it only contains:

global {
    usage-count no;
}
common {
    protocol C;
    syncer {
        rate 30M; 
    }
}

Next I created a new resouce file /etc/drbd.d/drbd0.res

resource drbd0 {
    protocol C;
    startup {
        wfc-timeout  0;
        degr-wfc-timeout 60;
        become-primary-on both;
    }
    net {
        cram-hmac-alg sha1;
        shared-secret "drbd0-secret";
        allow-two-primaries;
        after-sb-0pri discard-zero-changes;
        after-sb-1pri discard-secondary;
        after-sb-2pri disconnect;
    }
    on host1 {
        device /dev/drbd0;
        disk /dev/pve/lv4drbd;
        address 10.0.10.201:7780;
        meta-disk internal;
    }
    on host2 {
        device /dev/drbd0;
        disk /dev/pve/lv4drbd;
        address 10.0.10.202:7780;
        meta-disk internal;
    }
}

I added the IP address of the other host into each of the /etc/hosts files.

Next I started drbd on both nodes with

/etc/init.d/drbd start

I then initialized drbd metatdata on both nodes with

drbdadm create-md drbd0

Next I brought up the device on both nodes with

drbdadm up drbd0

I checked the status on both nodes with

drbd-overview

Next I started synchronization(should be instantaneous) from one node with

drbdadm -- --clear-bitmap new-current-uuid drbd0

Lastly, I restarted the drbd service on both nodes to enable Primary/Primary operation

/etc/init.d/drbd stop
/etc/init.d/drbd start

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ProxmoxVE 2.0: Shrinking the data volume

noreply@blogger.com (Jessie Evangelista) — Tue, 27 Mar 2012 21:00:28 PDT

After installing ProxmoxVE 2.0rc1, a data volume was created which makes use of most of the space on the drive.

I wanted to carve out a separate volume for some other use so I needed to shrink this data volume:

First, I unmounted the logical volume with:

umount /var/lib/vz

Then I proceeded to shrink the file system to the minimum size possible with:

resize2fs -Mf /dev/pve/data

Then I proceeded to reduce the size of the logical volume with:

lvreduce --verbose --extents -100000 /dev/pve/data

Then I proceeded to grow the file system back to occupy the now reduced volume with:

resize2fs -f /dev/pve/data

Lastly, I remounted the file system with:

mount /dev/pve/data /var/lib/vz

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FizzBuzz in Javascript

noreply@blogger.com (Jessie Evangelista) — Mon, 26 Mar 2012 05:07:17 PDT

Joel and company probably won't hire me since he only gets rockstar developers but here is my attempt at FizzBuzz

<script>
    for(var i=1;i<=100;i++){
        if(i%3 != 0  && i%5 != 0)
            document.write(i);
        if(i%3 == 0)
            document.write('Fizz');            
        if(i%5 == 0)
            document.write('Buzz');                    
        document.write(' ');
    } //end for loop
</script>

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dailyLooper bash script

noreply@blogger.com (Jessie Evangelista) — Fri, 23 Mar 2012 06:38:13 PDT

We needed to regenerate some data for the data warehouse so I had to run an extraction script once for each day of the month.

I wrote a simple bash script to make it easier to run a command or other scripts once for every day of a target month and year.

Code can be found below but may also be downloaded from here.

#!/bin/bash
usage(){
    echo "Usage: dailyLooper <year> <month> <script to run>"
    echo "Each date in the given month will be passed into the script in yyyy-mm-dd format"
}


CURRENT_MONTH=$(date +%m)
TARGET_YEAR=$1
TARGET_MONTH=$2

if [ "$#" -lt 3 ]; then
    usage
    exit 1
fi

if [ "$3" = "" ]; then
    SCRIPT="echo"
else
    SCRIPT=$3    
fi

#returns the date yesterday if target month is the current month
#otherwise returns the last date for the target month
lastDayOfMonth(){
    local _year=$1
    local _month=$2   
    if [ $_month -lt $CURRENT_MONTH ]; then
        echo $(date -d "${TARGET_YEAR}-${TARGET_MONTH}-01 + 1 month - 1 day" +%d)
    else
        echo $(date -d "yesterday" +%d)
    fi    
}


main(){
    local _lastDay=$(lastDayOfMonth $TARGET_YEAR $TARGET_MONTH)
    i=1
    while [ "$i" -le $_lastDay ]
    do
        local _date=$(date -d "${TARGET_YEAR}-${TARGET_MONTH}-${i}" +%Y-%m-%d)
        $SCRIPT $_date
        ((i++))
    done #end day of month loop
}

main

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Cheap and Safe File Storage on Linux

noreply@blogger.com (Jessie Evangelista) — Tue, 20 Mar 2012 05:26:02 PDT

I needed to setup a Samba file server using off the shelf desktop components.
It will be used in a small office with 5-10 clients.

Here are the relevant hardware specs:
Processor: i7
Memory: 16GB
Drives: 4 x 1TB sata drives
OS Installed: Ubuntu Sever 10.04LTS

The primary requirement is for the files to be fairly safe i.e. if the server crashes in the middle of saving a file then on restart, the file should return to the consistent state before the save operation. Performance is secondary to safety.

My initial plan was to use one drive for the OS and configure 3 drives in an mdraid level 5. After some research, I came across several references that state that mdraid level 10 works on odd numbered drives. It will work on 3 drives and even on 2. This looked like something I should try. I then had to decide what filesystem to use. I initially wanted to use xfs as I've heard and read a lot of good things about it.

After studying how to setup both mdraid and xfs, I started a thread on the linux-raid mailing list asking for best practice guidelines and guidance on using xfs with mdraid 10n2.

Several days of additional research guided by the comments on the mailing list thread resulted in a lot of learnings for me:

raid10n2 really works on 3 drives, I had my doubts at first but now I finally get how it can work with just three drives
drive sector size can be either 512b or 4k which can lead to mis-aligned partitions and have a negative impact on performance
ext4 provides the option: data=journal which makes it safer than xfs at the cost of some performance

The table below shows the average of the benchmark results I got. Yes, I know bonnie++ only tests sequential write/rewrite/read and some file operations and is not necessarily representative of the workload but IMHO, it is better than nothing. This was how things were setup for the benchmark:

a 50GB primary partition was created on each device located 1GB from the start of the disk for partition alignment
the md raid device is created on top of the primary partition created on each device
the chunk was set to 64k
the results below are for raid5 and raid10n2 only but I also tried raid10f2 and raid10n2
raid 10f2 had better read performance but slower write compared to raid 10n2
raid 10o2 performed quite closely to raid 10n2
the benchmark was run three times and the average was taken

Bonnie 1.96		Sequential Output				Sequential Input		Random Seeks
64k chunk	Size	Block		Rewrite		Block		Random Seeks
ext4/mdraid		K/sec	% CPU	K/sec	% CPU	K/sec	% CPU	/sec	% CPU
raid5 data=ordered	32G	144430	11	68725	9.67	249364	21	280.33	9.33
raid5 data=journal	32G	25077	4.67	21605	5	267283	22.33	293.67	6
raid10n2 data=ordered	32G	137365	8	69940	9	209180	16	365.03	11.67
raid10n2 data=journal	32G	56249	6	37491	6	206548	16	389.00	8

For those interested, you can find/get the script I used here.

I modified this script to run my tests.

You can find the raw results here.

You can also find the debug info here.

I am considering re-running the tests but this time with iozone instead of bonnie++ so that I can get scores for random read and write.

Next, I plan to do pull-the-plug testing on ext4,data=journal on top of raid10n2 while doing streaming writes of a huge file over samba. I plan to use 2 different video files greater than 3GB. First I will copy file1 to the samba share and time it. I will then compute a checksum for file1 both locally and on the samba server. The computed checksum should be equal. Next, I will compute a checksum for file2 locally. It should be different from the value computed for file1. I will then move file1 to another directory and rename file2 to the the same name as file1. I will then attempt to copy the new file1 to the samba server. Halfway into the copy, I will pull the plug of the samba server. Next I will restart the samba server and recompute the checksum of file1. It should still be equal to the computed copy before.

If the system behaves as expected, I will go with ext4,data=journal on top of raid10n2.

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Check disk write-caching

noreply@blogger.com (Jessie Evangelista) — Wed, 14 Mar 2012 06:10:14 PDT

I'm investigating the performance of file systems and found myself needing to check if write-caching was enabled for my disk.

hdparm -W /dev/sda

To turn off write-caching, do

hdparm -W0 /dev/sda

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Globe UnliAllTxt with PlaySMS

noreply@blogger.com (Jessie Evangelista) — Mon, 12 Mar 2012 01:15:22 PDT

We are using PlaySMS on top of SMS Server Tools 3(http://smstools3.kekekasvi.com/index.php?p=) for our SMS gateway.

We wanted to take advantage of the Unlimited All Text Promo of Globe. I couldn't get the USB modem to register for the promo.

Registering thru a phone with the same SIM works. After reading the documentation of SMS Server Tools, I finally got it to work.

First I had to set the correct SMSC for the modem.

smsc = 639170000130

Next, I had to manually craft an SMS file that will be sent to the shorcode:8888.

To: s8888
Modem: GLOBE

UALLPLUS25

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ProxmoxVE 2.0rc1 Notes:Setup

noreply@blogger.com (Jessie Evangelista) — Wed, 07 Mar 2012 06:19:22 PST

This is Part#1 of a series of posts on my experience with Proxmox 2.0rc1.

I was tasked to look for a suitable solution to build an internal cloud/virtualization infrastructure and I've decided to spend some time with ProxmoxVE 2.0rc1.

The list below is the hardware available to me:
2 desktop computers
Intel i3-530
4GB DDR3
1TB Hard drive

Things I want to try:
- benchmark disk/file IO performance of host system
- benchmark dis/file IO performance of guest system
- openvz live migration
- kvm live migration
- HA storage for the VM using DRBD
- ProxmoxVE HA i.e. guest starting on secondary node when primary node goes down
- openvz ubuntu server 10.04LTS guest running tomcat6 on sun-java6-jdk
- kvm ubuntu server 10.04LTS guest running tomcat6 on sun-java6-jdk

Installing ProxmoxVE 2.0rc1 on the hardware was fairly straight forward.
The installer took over the whole 1TB drive and partitioned it on its own.

running fdisk -l /dev/sda && df -Th revealed:
- /dev/sda1 is 495MB ext3 mounted on /boot
- dev/sda2 is 999.5GB LVM

running pvscan && vgscan revealed:
- /dev/sda2 was configured as an lvm2 physcial volume
- a volume group named pve was created by proxmox

running lvscan && mount revealed:
- a 4GB /dev/pve/swap volume was created for swap
- a 96GB /dev/pve/root ext3 volume mounted as the root file system
- a 899GB /dev/pve/data ext3 volume mounted on /var/lib/vz

Next I updated ProxmoxVE 2.0rc1 which is Debian based.
The host is behind a proxy server so to update I ran:

export http_proxy=http://10.0.0.1:3128

apt-get update && apt-get -y upgrade

I proceeded to install some useful tools:
apt-get install screen dstat

Next, I configured NTP to sync to a time server on the local network

Next I downloaded an openvz template for ubuntu 10.04LTS and proceeded to create and run a guest.

I ran across an annoying bug while accessing the guest using the console. Tab completion was not working which made it difficult to work on the web console. I found a work around and made a separate post for the web console tab fix

Stay tuned for my next post in this series: Setting up DRBD backed storage even with just one hard disk

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ProxmoxVE 2.0rc1 web console tab fix

noreply@blogger.com (Jessie Evangelista) — Wed, 07 Mar 2012 06:14:48 PST

I ran across an annoying bug while accessing the guest using the console. Tab completion was not working which made it difficult to work on the web console. I found a work around which modifies /usr/share/pve-manager/ext4/pvemanagerlib.js with:

cp /usr/share/pve-manager/ext4/pvemanagerlib.js /root/pvemanagerlib.js.bak

cat /usr/share/pve-manager/ext4/pvemanagerlib.js | \
sed "s/'Show Controls', value: 'No'/'Show Controls', value: 'Yes'/" \
> /usr/share/pve-manager/ext4/pvemanagerlib.js

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Mount a Proxmox KVM raw image in an LVM over DRBD

noreply@blogger.com (Jessie Evangelista) — Wed, 07 Mar 2012 02:45:33 PST

Hardware:
2 desktop computers
Intel i3-530
4GB DDR3
1TB Hard drive

Setup:
- 2 node cluster of ProxmoxVE 2.0-35/d07f49c3(rc1)
- LVM volume group named drbd_storage created on top of a drbd block device
- Installed Ubuntu Server 10.04LTS in a kvm container named ubuntu-kvm-template
- proxmox created a logical volume in drbd_storage named vm-108-disk-1

I want to mount the disk so that I can check something out. Apparently it is not that simple.

I eventually figured it out thru trial and error of suggestions across serveral sources.

losetup /dev/loop0 /dev/drbd_storage/vm-108-disk-1
fdisk -l /dev/loop0
apt-get install kpartx
kpartx -av /dev/loop0
pvscan
vgscan
lvscan
vgchange -ay
lvscan
mkdir -p /tmp/108
mount /dev/ubuntu-kvm-template/root /tmp/108
umount /mnt/108
lvchange -an /dev/ubuntu-kvm-template/*
kpartx -dv /dev/loop0
losetup -d /dev/loop0

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Finding the largest sized directory

noreply@blogger.com (Jessie Evangelista) — Fri, 16 Dec 2011 01:00:07 PST

One of our servers keeps running out of disk space. To address this, we needed to find out which folders had the largest size.

On ubuntu server 10.04LTS, this is how we found the directories with the greatest size:

du -m /var/log | sort -n -r | head -n 10

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Creating a Latin1 PostgreSQL database in Ubuntu 10.04LTS

noreply@blogger.com (Jessie Evangelista) — Tue, 13 Dec 2011 22:27:30 PST

I've encountered this problem several times already and I've finally stumbled upon a solution.

The Problem:

We were tasked to move a postgresql database from an centos based server to a new ubuntu based server. The database was in latin1 encoding.

On the new ubuntu based server, creating a database with latin1 encoding results in an error.
Command: createdb -E LATIN1 --template template0 trial
Result:
createdb: database creation failed: ERROR: encoding LATIN1 does not match locale en_PH.utf8
DETAIL: The chosen LC_CTYPE setting requires encoding UTF8

The Fix:

First we needed to modify /var/lib/locales/supported.d/local and add the line:
en_PH.ISO-8859-1 ISO-8859-1

Next we had to regenerate the locale files with:
sudo dpkg-reconfigure locales

Afterwards we were able to create a latin1 database with:
createdb -E LATIN1 --template template0 --locale en_PH.ISO-8859-1 trial

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Changing hostname on Ubuntu Server 10.04LTS

noreply@blogger.com (Jessie Evangelista) — Thu, 17 Nov 2011 01:05:58 PST

I found out the hard way that it's changing the name of an Ubuntu Server 10.04LTS was not as straight forward as I initially thought. To save you and me the trouble and for future reference, I document how I did it here.

hostname NEW_NAME
echo NEW_NAME > /etc/hostname
cat /etc/hosts | sed s/OLD_NAME/NEW_NAME/g > /etc/hosts.new
mv /etc/hosts /etc/hosts.old
mv /etc/hosts.new /etc/hosts

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Monitoring Tomcat6 with VisualVM on Ubuntu

noreply@blogger.com (Jessie Evangelista) — Wed, 02 Nov 2011 04:36:51 PDT

One of our applications running on Tomcat6 was encountering an issue which was drastically affecting the delivery of services to our clients. To diagnose this, we needed to monitor the state of the virtual machine running Tomcat6. This is what I had to do:

Assumptions:
- tomcat6 installed on an ubuntu server instance
- firewall on the server instance is enabled
- server has non public ip address: 10.0.0.1
- client machine installed with java6 which includes visualvm

1) download catalina-jmx-remote.jar and copy it into the tomcat6 lib folder. At the time of this writing, I found it here: http://apache.opensourceresources.org/tomcat/tomcat-6/v6.0.33/bin/extras/

2) modify /etc/defaults/tomcat6, add the following line to JAVA_OPTS

-Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Djava.rmi.server.hostname=10.0.0.1

3) modify /etc/tomcat6/server.xml, add the following line inside the server block near the other listeners:

<Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener"
rmiRegistryPortPlatform="8086" rmiServerPortPlatform="8086" />

4) enable access to port 8086

ufw allow 8086

5) restart tomcat6

service tomcat6 restart

6) start visualvm on the client machine and add a jmx connection: 10.0.0.1:8086

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Installing Oracle 10g XE on Ubuntu 10.10

noreply@blogger.com (Jessie Evangelista) — Sun, 18 Sep 2011 06:46:36 PDT

Found myself needing to install oracle 10g xe on Ubuntu 10.10.

add-apt-repository "deb http://oss.oracle.com/debian unstable main non-free"
wget http://oss.oracle.com/el4/RPM-GPG-KEY-oracle  -O- | sudo apt-key add -
apt-get install oracle-xe-universal
/etc/init.d/oracle-xe configure
/etc/init.d/oracle-xe enable

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Creating a DVD Video Disc

noreply@blogger.com (Jessie Evangelista) — Thu, 14 Jul 2011 07:55:53 PDT

I was asked to create a dvd out of 5 flash video files from youtube.
Also had to add 8 seconds of chapter title video using a png image for each chapter

Used devede on ubuntu.

create frames.txt:

for i in `seq 1 5`; do echo title.png; done > frames.txt

used mencoder:

mencoder mf://@frames.txt -mf w=800:h=600:fps=1:type=png -ovc lavc -lavcopts vcodec=mpeg4:mbd=2:trell -oac copy -o output.avi

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Setting up Apache2 and Tomcat6 on Ubuntu 10.04

noreply@blogger.com (Jessie Evangelista) — Wed, 15 Jun 2011 02:18:50 PDT

This is a short post on setting up Apache2 and Tomcat6

Install Java

apt-get -y install python-software-properties
add-apt-repository "deb http://archive.canonical.com/ lucid partner"
apt-get update
apt-get install -y sun-java6-jdk

Install tomcat6 with apache2 support

apt-get -y install tomcat6 libtcnative-1 libapache2-mod-jk

Setup worker.properties with the following values:
workers.tomcat_home=/usr/share/tomcat6
workers.java_home=/usr/lib/jvm/java-6-sun

nano /etc/libapache2-mod-jk/workers.properties

Modify /etc/apache2/mods-available/jk.load

cat >>/etc/apache2/mods-available/jk.load <<EOF
JkWorkersFile /etc/libapache2-mod-jk/workers.properties
JkLogFile /var/log/apache2/mod_jk.log
JkLogLevel error
EOF

Setup virtual host

cat >/etc/apache2/sites-available/test.henyo.com <<EOF
NameVirtualHost *
<VirtualHost *>
        ServerName test.henyo.com
        JkMount /* ajp13_worker
</VirtualHost>
EOF

Activate the site

a2ensite test.henyo.com

Setup tomcat for ajp13

nano /etc/tomcat6/server.xml

Restart tomcat and apache2

service tomcat6 restart
service apache2 restart

Install and configure UFW

apt-get install ufw
ufw allow ssh
ufw allow http
ufw enable

Install and configure Tripwire

apt-get install tripwire

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Setting up a Spring Data JPA Project

noreply@blogger.com (Jessie Evangelista) — Sun, 17 Apr 2011 07:16:03 PDT

This post is about setting up a Maven Project based on Spring Data JPA. I spent a few hours today nailing it down. Hopefully it saves someone some time to bring a project up quickly.

- Spring Framework based application
- makes use of Spring Data JPA for easy Repositories
- makes use of JPA 2.0 persistence with EcliplseLink
- JUnit4 and spring-test
- Logging using SL4J to Log4J

For the impatient, I uploaded a sample project on github: spring-data-jpa-trial

You can also download the tar ball or zip file from these links.

I started with a blank Maven Project created with STS 2.5.2.SR1 created using
the New Maven Project wizard checking the Create a simple project(skip archetype selection).

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>test</groupId>
<artifactId>test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>test</name>
<description>test</description>
</project>

Added some entries to the pom file to setup 1.6

<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.3.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
</plugins>
</build>

Setup spring-data-jpa dependency

<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.0.0.M2</version>
<exclusions>
<exclusion>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
</exclusion>
</exclusions>
</dependency>

<repository>
<id>spring-milestone</id>
<name>Spring Maven MILESTONE Repository</name>
<url>http://maven.springframework.org/milestone</url>
</repository>

Setup persistence dependecies

<!-- Persistence dependencies -->
<dependency>
<groupId>hsqldb</groupId>
<artifactId>hsqldb</artifactId>
<version>1.8.0.10</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-instrument</artifactId>
<version>${spring.framework.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.eclipse.persistence</groupId>
<artifactId>eclipselink</artifactId>
<version>2.2.0</version>
<scope>runtime</scope>
</dependency>
<repository>
<id>EclipseLink Repo</id>
<url>http://download.eclipse.org/rt/eclipselink/maven.repo</url>
</repository>

Setup logging dependencies as discussed in the Spring Framework Reference Docs

<dependency>
<groupId>org.slf4j</groupId>
<artifactId>jcl-over-slf4j</artifactId>
<version>${sl4j.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${sl4j.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${sl4j.version}</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
<scope>runtime</scope>
</dependency>

Setup Testing Dependencies

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.8.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.framework.version}</version>
<scope>test</scope>
</dependency>

<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.8</version>
<configuration>
<includes>
<include>**/*Tests.java</include>
</includes>        
<argLine>-javaagent:spring-instrument-3.0.5.RELEASE.jar</argLine>
</configuration>
</plugin>

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