Migrate to Cloud Amazon EC2 Cloud Computing|Company: MySQL AB

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It’s Phab! That makes your life easier

Wednesday, August 13th, 2014 | Posted in Cloud computing

We have been using plenty of different tools for tracking bugs/product management/project management/to do lists/code review; such as ClearCase, ClearQuest, Bugzilla, Github, Asana, Pivotal Tracker, Google Drive etc. We found Phabricator as a “Too Good To Be True” software engineering web application platform originally developed at Facebook. It has code review, wiki, repository browsing,tickets and a lot more to make Phab more fabulous.

Phabricator is an open source collaboration of web applications which help software companies to build better software. It is a suite of applications. Following are the most important tools in phabricator :
Maniphest – Bug tracker/task management tracker
Diffusion- source code browser
Differential – code review tool that allows developers to easily submit reviews to one another via command line tool when they check in code using Git or Subversion
Phriction – wiki tool

How to setup and configure the code review and project management tool – Phabricator

Installation

Server – 4GB Digital ocean droplet
OS – Ubuntu 14.04

1. Install dependencies

apt-get install mysql-server apache2 dpkg-dev php5 php5-mysql php5-gd php5-dev php5-curl php-apc php5-cli php5-json

2. Get code

#cd /var/www/codereview

git clone https://github.com/phacility/libphutil.git

git clone https://github.com/phacility/arcanist.git

3. Configure virtual host entry

#add below lines

#######################################################################

DocumentRoot /var/www/codereview/webroot
RewriteEngine on
RewriteRule ^/rsrc/(.*) – [L,QSA]
RewriteRule ^/favicon.ico – [L,QSA]
RewriteRule ^(.*)$ /index.php?__path__=$1 [B,L,QSA]
Order allow,deny
allow from all
#######################################################################
4. Enable the virtual host entry for phabricator.

# a2ensite phabricator.conf
# service apache2 reload

5. Configure the MySQL database configuration for phabricator

– create database
# /var/www/codereview/phabricator/bin/config set mysql.user mysql_username
# /var/www/codereview/phabricator/bin/config get mysql.pass mysql_password
# /var/www/codereview/phabricator/bin/config get mysql.host mysql_host
# /var/www/codereview/phabricator/bin/config storage upgrade
-tweak mysql

Open /etc/mysql/my.cnf and add the following line under [mysqld] section:

sql-mode = STRICT_ALL_TABLES

#service mysql restart

Set the Base URI of Phabricator install

# /var/www/codereview/phabricator/bin/config set phabricator.base-uri

(eg: phabricator.your-domain.com)

Configure Outbound Email – External SMTP (Google Apps)

Set the following configuration keys using /var/www/codereview/phabricator/bin/config set value

– metamta.mail-adapter -> PhabricatorMailImplementationPHPMailerAdapter
– phpmailer.mailer -> smtp
– phpmailer.smtp-host -> smtp.gmail.com
– phpmailer.smtp-port -> 465
– phpmailer.smtp-user -> Your Google apps mail id
– phpmailer.smtp-password -> set to your password used for authentication
– phpmailer.smtp-protocol -> ssl

Start the phabricator daemons

You can start all the phabricator deamons using the script
# /var/www/codereview/phabricator/bin/phd start
To start daemons at the boot time, add this entry to the file /etc/rc.local

/var/www/codereview/phabricator/bin/phd start

Diffusion repository hosting with git

1. Install git

#apt-get install git

2. Create a local repository directory:

#mkdir -p /data/repo

3. Edit the repository.default-local-path key to the new local repository directory.

Go to the Config -> Repositories -> repository.default-local-path

4. Configure System user accounts

Phabricator uses as many as three user accounts. These are system user accounts on the machine Phabricator runs on, not Phabricator user accounts.

* daemon-user – The user the daemons run as

We will configure the root user to run the daemons

* www-user – The user the web server run as

We will use www-data to be the web user

* vcs-user – The user that users will connect over SSH as

We will configure git user to the vcs-user

To enable SSH access to repositories, edit /etc/sudoers file using visudo to contain:

#includedir /etc/sudoers.d
git ALL=(root) SETENV: NOPASSWD: /usr/bin/git-upload-pack, /usr/bin/git-receive-pack, /usr/bin/git

Since we are going to enable SSH access to the repository, ensure the following holds good.

– Open /etc/shadow and find the line for vcs-user, git.

The second field (which is the password field) must not be set to !!. This value will prevent login. If it is set to !!, edit it and set it to NP (“no password”) instead.

– Open /etc/passwd and find the line for the vcs-user, git.
The last field (which is the login shell) must be set to a real shell. If it is set to something like /bin/false, then sshd will not be able to execute commands. Instead, you should set it to a real shell, like /bin/sh.

– Use phd.user as our daemon user;
# /var/www/phab/phabricator/bin/config phd.user root
# /var/www/phab/phabricator/bin/config set diffusion.ssh-user git

5. Configuring SSH

We will move the normal sshd daemon to another port, say 222. We will use this port to get a normal login shell. We will run highly restrictive sshd on port 22 managed by Phabricator.

Move Normal SSHD

– make a backup of sshd_config before making any changes.

#cp /etc/ssh/sshd_config /etc/ssh/sshd_config.backup

– Update /etc/ssh/sshd_config, change the port to some othert port like 222.

Port 222

– Restart sshd and verify that you are able to connect to the new port

ssh -p 222 user@host

Configure and start Phabricator SSHD

We now configure and start a second SSHD instance which will run on port 22. This instance will use special locked down configuration that uses Phabricator to handle the authentication and command execution.

– Create a phabricator-ssh-hook.sh file

– Create a sshd_phabricator config file

– Start a copy of sshd using the new configuration

Create phabricator-ssh-hook.sh: Copy the template in phabricator/resources/sshd/ phabricator-ssh-hook.sh to somewhere like /usr/lib/phabricator-ssh-hook.sh and edit it to have the correct settings

##############################################################

#!/bin/sh

# NOTE: Replace this with the username that you expect users to connect with.
VCSUSER=”git”

# NOTE: Replace this with the path to your Phabricator directory.
ROOT=”/var/www/codereview/phabricator”

if [ “$1” != “$VCSUSER” ];
then
exit 1
fi

exec “$ROOT/bin/ssh-auth” $@
##############################################################

Make it owned by root and restrict editing;

#sudo chown root /usr/lib/phabricator-ssh-hook.sh
#chmod 755 /usr/lib/phabricator-ssh-hook.sh

Create sshd_config for Phabricator: Copy the template in /phabricator/sshd/sshd_config.phabricator.example to somewhere like /etc/ssh/sshd_config.phabricator

Start Phabricator SSHD

#sudo /usr/sbin/sshd -f /etc/ssh/sshd_config.phabricator

Note:-
Add this entry to the /etc/rc.local to start the daemon on startup.

If you did everything correctly, you should be able to run this;

#echo {} | ssh git@phabricator.your-company.com conduit conduit.ping

and get a response like this;

{“result”:”phab-server”,”error_code”:null,”error_info”:null}

You should now be able to access your instance over ssh on port 222 for normal login and administrative purposes. Phabricator SSHD runs on port 22 to handle authentication and command execution.

6. To create a git repository

Go to Diffusion -> New Repository -> Create a New Hosted Repository

Upgrade Phabricator

Since phabricator is under development, you should update frequently. To update phabricator:

– Stop the web server
– Run git pull in libphutil/, arcanist/, and phabricator.
– Run phabricator/bin/storage upgrade.
– Restart the web server.
Also you can use a script similar to this one to automate the process:
http://www.phabricator.com/rsrc/install/update_phabricator.sh

Apache on the Cloud – The things you should know

Wednesday, May 8th, 2013 | Posted in Cloud computing

LAMP forms the base of most web applications. As the load on an server increases, the bottlenecks in the underlying infrastructure become more apparent in the form of slow response to user requests.

To overcome this slow response the primary choice of most people is to add more hardware resources ( incase of AWS increasing the instance type). This will definitely increases performance but will cost you more money. The webserver and database eat most of the resources. Most commonly used web server is apache and database is MySQL. So if we can optimize these two we can improve the performance.

Apache optimization techniques can often provide significant acceleration boosts even when other acceleration techniques are in use, such as a CDN. mod_pagespeed is a module from Google for Apache HTTP Servers that can improve the page load times of your website. you can read more on this from here. If you want to deploy a PHP app on AWS Cloud, Its better to using some kind of caching mechanism. Its already discussed in our blog .

Once we came into a situation where we have to use a micro instance for a web server with less than 500 hits a day

When the site started running live, and we feel like disappointed. when accessing website, it would sometimes pause for several seconds before serving the requested page. It took hours to figure out what was going on. finally we run the command top and quickly discovered that when the site was accessing by certain amount of users the CPU would spike, but the spike was not the typical user or system CPU. For testing what’s happening in server we used the apache benchmark tool ‘ab’ and run the following command on localhost.

#ab -n 100 -c 10 http://mywebserver.com/

This will show how fast our web server can handle 100 requests, with a maximum of 10 requests running concurrently. In the meantime we were monitoring the output of top command on web server.

For further investigation we started with sar – Linux command to Collect, report, or save system activity information

#sar 1

According to amazon documentation “Micro instances (t1.micro) provide a small amount of consistent CPU resources and allow you to increase CPU capacity in short bursts when additional cycles are available”.

If you use 100% CPU for more than a few minutes, Amazon will “steal” CPU time from the instance, meaning that they throttle your instance. This last as long as five minutes, and then you get a few seconds of 100% again, then the restrictions are back. This will effect your website, making it slow, and even timing-out requests. basically means the physical hardware is busy and the hypervisor can’t give the VM the amount of CPU cycles it wants.

Real tuning required on prefork. This is where we can tell apache to only generate so many processes. The defaults values are high, and which cant be handled by micro instance. Suppose you get 10 concurrent requests for a php page and require around 64MB of RAM when requested (you have to make sure that php memory_limit is above that value). That’s around 640MB of RAM on micro instance of 613MB RAM. This is the case with 10 connections – apache is configured to allow 256 clients by default, We need to scale these down , normally with 10-12 MaxClients. As per out case, this is still a huge number because 10-12 concurrent connections would use all our memory. If you want to be really cautious, make sure that your max memory usage is less than 613MB. Something like 64M php memory limit and 8 max clients keeps you under your limit with space to spare – this helps ensure that our MySQL process when your server is under load.

Maxclients an important tuning parameter regarding the performance of the Apache web server. We can calculate the value of this for a t1.micro instance

Theoretically,

MaxClients =(Total Memory – Operating System Memory – MySQL memory) / Size Per Apache process.

t1.micro have a server with 613MB of Total memory. Suppose We are using RDS instead of mysql server.

Stop apache and run

#ps aux | awk ‘{sum1 +=$4}; END {print sum1}’.

we will get the amount of memory thats used by processes other than apache.

Suppose we get a value around 30.

from top command we can check the average memory that each apache resources use.

suppose its 60mb.

Max clients = (613 – 30 ) 60 = 9.71 ~ 10 approx …

Micro instances are awesome, especially when cost becomes a major concern, however that they are not right for all applications. A simple website with only a few hundreds hits a day will do just fine since it will only need CPU in short bursts.

For Servers that serves dynamic content, better approach is to employ a reverse-proxy. This would be done this apache’s mod_proxy or Squid. The main advantages of this configurations are content caching, load balancing etc. Easy method is to use mod_proxy and the ProxyPass directive to pass content to another server. mod_proxy supports a degree of caching that can offer a significant performance boost. But another advantage is that since the proxy server and the web server are likely to have a very fast interconnect, the web server can quickly serve up large content, freeing up a apache process, why the proxy slowly feeds out the content to clients

If you are using ubuntu, you can enable module by

#a2enmod proxy

#a2enmod proxy_http

and in apache2.conf

ProxyPass / http://192.168.1.46/

ProxyPassReverse / http://192.168.1.46/

The ProxyPassreverse directive captures the responses from the web server and masks the URL as it would be directly responded by the Apache hiding the identity/location of the web server. This is a good security practice, since the attacker won’t be able to know the ip of our web server.

Caching with Apache2 is another important consideration. We can configure apache to set the Expires HTTP header, max-age directive of the Cache-Control HTTP header of static files ,such as images, CSS and JS files, to a date in the future so that these files will be cached by your visitors browsers. This saves bandwidth and makes web site appear faster if a user visits your site for a second time, static files will be fetched from the browser cache

#a2enmod expires

edit /etc/apache2/sites-available/default

  <IfModule mod_expires.c>
               ExpiresActive On
               ExpiresByType image/gif “access plus 4 weeks”
               ExpiresByType image/jpg “access plus 4 weeks”

</IfModule>

This would tell browsers to cache .jpg, .gif files for four week.

If your server requires a large amount of read / write operations, you might consider provisioned IOPS ebs volumes on your server. This is really effective if you use database server on ec2 instances. we can use iostat on the command line to take a look at your read/sec and write/sec. You can also use CloudWatch metrics to determine read and write operations.

Once we move to the security side of apache, our major concern is DDos attacks. If a server is under a DDoS attack, it is quite difficult to detect the attack before the damage is done. Attack packets usually have spoofed source IP addresses. Hence, it is more difficult to trace them back to their real source. The limit on the number of simultaneous requests that will be served by Apache is decided by the MaxClients directive, and is set to safe limit, by default. Any connection attempts over this limit will normally be queued up.

If you want to protect your apache against DOS, DDOS attacks use mod_evasive module. This module is designed specifically as a remedy for Apache DoS attacks. This module will allow you to specify a maximum number of requests executed by the same IP address. If the limit is reached, the IP address is blacklisted for the time period you specify.

PHP Caching : The way to speed up PHP sites.

Tuesday, March 19th, 2013 | Posted in hosting

There are many sites which is built in PHP. PHP provides the power to simply ‘pull’ content from an external source. it could just as easily be an MySQL database or an XML file etc.

The downside to this is processing time, each request for one page can trigger multiple database queries, processing of the output, and formatting it for display. This can be quite slow on complex sites (or slower servers). Dynamic sites probably have very little changing content, this page will almost never be updated after the day it is written. Each time someone requests it the scripts goes and fetches the content, applies various functions and filters to it, then outputs it to you

This is where caching can help us out, instead of regenerating the page every time, the scripts running this site generate it the first time they’re asked to, then store a copy of what they send back to your browser. The next time a visitor requests the same page, the script will know it’d already generated one recently, and simply send that to the browser without all the hassle of re-running database queries or searches.

Different Caching mechanism are discussed below.

APC

APC stands for Alternative PHP Cache, and is a free and open opcode cache for PHP. It provides a robust framework for caching and optimizing PHP performance. APC also provides a user cache for storing application data. APC for caches that do not change often and will not grow too big to avoid fragmentation. The default setting of APC will allow you to store 32 MiB for the opcode cache and the user cache combined

Installing apc on ubuntu

#apt-get install php-apc

edit apc.ini ; default location on new php5 is –> /etc/php5/conf.d/20-apc.ini

extension = apc.so;  uncomment this line   
apc.shm_segments=1;   ( by default its enabled .. give 0 to disable)

you can customize your values here. for getting the default values install php5-cli and from command line run

#php -i | grep apc

For monitoring apc cache hits and miss, apc providing a php script. which is located at /usr/share/doc/php-apc/apc.php. Copy this file to your document root and you will be able to monitor your apc status.

http://localhost/apc.php

for performance benchmarking we created two php files

test1.php

<?php 
         $start = microtime(true);
         for ($i = 0; $i < 500000; $i++)
             {
                include('test_include.php');
             }
         $end = microtime(true);          echo "Start: " . $start . "<br />";
         echo "End: " . $end . "<br />";
         echo "Diff: ". ($end-$start) . "<br />";
?>

test2.php

<?php
          $t =    "migrate2cloud";
 ?>

Without apc…

Start: 1360937874.8965 
End: 1360937883.1506 
Diff: 8.2541239261627

With apc..

Start: 1360937935.5746 
End: 1360937936.7291 
Diff: 1.1545231342316

without apc it took 8 seconds to complete the request .. with apc.. 1.15 seconds..

Memcached

Memcached system uses a client–server architecture. The servers maintain a key–value associative array; the clients populate this array and query it. Keys are up to 250 bytes long and values can be at most 1 megabyte in size. Clients use client-side libraries to contact the servers which, by default, expose their service at port 11211. Amazon provides a Service called Amazon elasticache for memcache through which we can configure memcache clusters for caching purposes.

installation and configuration

apt-get install memcached 
apt-get install php5-memcached

enable memcache module in /etc/php5/apache2/conf.d/20-memcached.ini or in php.ini

edit php.ini 
session.save_handler = memcached 
extension=memcache.so
extension=memcached.so

Restart apache and memcache..

php script used for memcache testing..

 
<?php
//memcached simple test  
$memcache = new Memcache;
$memcache->connect('localhost', 11211) or die ("Could not connect");
$key = md5('42data');  //something unique  
for ($k=0; $k<5; $k++) {
$data = $memcache->get($key);
    if ($data == NULL) {
       $data = array();
       //generate an array of random shit  
       echo "expensive query";
       for ($i=0; $i<100; $i++) {
           for ($j=0; $j<10; $j++) {
               $data[$i][$j] = 42;  //who cares  
           }
       }
       $memcache->set($key,$data,0,3600);
    } else 
 {
       echo "cached";
    }  }

You can monitor memcache using phpmemcacheadmin

http://code.google.com/p/phpmemcacheadmin/

Varnish – Cache

Varnish has a concept of “backend” or “origin” servers. A backend server is the server providing the content Varnish will accelerate. Our first task is to tell Varnish where it can find its content. open the varnish default configuration file. Iif you installed from a package it is probably /etc/varnish/default.vcl.

Somewhere in the top there will be a section that looks a bit like this.:

backend default { .host = "127.0.0.1"; .port = "80"; }

Change the port number to your apache ( or whatever the webserver you are using) port number.

this piece of configuration defines a backend in Varnish called default. When Varnish needs to get content from this backend it will connect to port 80 on localhost (127.0.0.1).

# varnishd -f /etc/varnish/default.vcl -s malloc,1G -T 127.0.0.1:2000 -a 0.0.0.0:80

The -f options specifies what configuration varnishd should use.

The -s options chooses the storage type Varnish should use for storing its content

-T 127.0.0.1:2000 — Varnish has a built-in text-based administration interface

-a 0.0.0.0:80 — specify that I want Varnish to listen on port 80

For logging varnish — In terminal window you started varnish type varnishlog

When someone accessing your page you will get log like

#varnishlog
11 SessionOpen c 127.0.0.1 58912 0.0.0.0:80 
11 ReqStart c 127.0.0.1 58912 595005213 
11 RxRequest c GET 
11 RxURL c / 
11 RxProtocol c HTTP/1.1 
11 RxHeader c Host: localhost:80
11 RxHeader c Connection: keep-alive

Where not to use Caching

Caching should not be used for some things like search results, forums etc… where the content has to be upto the times and changes depending on user’s input. It’s also advisable to avoid using this method for things like a Flash news page, in general dont use it on any page that you wouldn’t want the end users browser or proxy to cache.

Migrate Mysql database to Mongodb

Friday, February 15th, 2013 | Posted in Cloud computing

In recent years, we have seen a growing interest in database management systems that differ from the traditional relational model. At the heart of this is the concept of NoSQL, a term used collectively to denote database software that does not use the Structured Query Language (SQL) to interact with the database. One of the more notable NoSQL projects out there is MongoDB, an open source document-oriented database that stores data in collections of JSON-like documents. What sets MongoDB apart from other NoSQL databases is its powerful document-based query language, which makes the transition from a relational database to MongoDB easy because the queries translate quite easily.

This new class of databases seems to solve many of the bottlenecks in MySql and other relational databases. It will give you shear performance, self replication and scalability at not cost because it open source. MongoDB has plenty of drivers for other scripting and high-level languages I use PHP so I download the PHP driver. You can see the supported list here: http://www.mongodb.org/display/DOCS/Drivers. In this blog I convert a MySQL database using PHP to MongoDB.

First you install MongoDB, you can do it by checking the previous blog. Check this link

Then we run the script to convert a Mysql DB to Mongodb.

create a new file called MySqltoMongodb.php , In that file please copy paste the below contants (please give your Mysql DB details as well as your Mongodb details)

<?php
// mysql settings
$mydb = “database”;
$myconn = mysql_connect(‘localhost’,’user’,’password’);
$setmydb = mysql_select_db( $mydb );
$mytables = getMyTables( $mydb );
//mongo db settings
$modb = “database”;
$moConnect=”mongodb://user:password@localhost”;
function getMyTables( $dbname ) {
$tables = array();
$sql = mysql_query(“SHOW TABLES FROM $dbname “) or die(“Error getting tables from $dbname”);
if( mysql_num_rows( $sql ) > 0 ) {
while( $table = mysql_fetch_array( $sql ) ) {
$explain = explainMyTable( $table[0] );
$tables[$table[0]] = $explain;
}
}
return $tables;
}
function explainMyTable( $tbname ) {
$explain = array();
$sql = mysql_query(“EXPLAIN $tbname”) or die(“Error getting table structure”);
$i = 0;
while( $get = mysql_fetch_array( $sql ) ) {
array_push( $explain, $get[0] );
$i++;
}
return $explain;
}
function checkEncode($string) {
if( !mb_check_encoding($string,’UTF-8′)) {
return mb_convert_encoding($string,’UTF-8′,’ISO-8859-1′);
} else {
return $string;
}
}
try {
$moconn = new Mongo($moConnect);
$modb = $moconn->selectDB( $modb );
} catch(MongoConnectionException $e) {
die($e.”Problem during mongodb initialization. Please start mongodb server.”);
}
foreach( $mytables as $table => $struct ) {
$sql = mysql_query(“SELECT * FROM $table LIMIT 0 , 500000″) or die( mysql_error() );
$count = mysql_num_rows( $sql );
// Starts new collection on mongodb
$collection = $modb->$table;
// If it has content insert all content
if( $count > 0 ) {
while( $info = mysql_fetch_array( $sql, MYSQL_NUM )) {
$infosize = count( $info );
$mosql = array();
for( $i=0; $i < $infosize; $i++ ) {
if(!empty($struct[$i]))
$mosql[$struct[$i]] = checkEncode($info[$i]);
}
$collection->insert($mosql);
}
// Only create a new entry empty
} else {
for( $i=0; $i < $infosize; $i++ ) {
if(!empty($struct[$i]))
$mosql[$struct[$i]] = ”;
}
$collection->insert($mosql);
}
}
echo “Done! Please, check your MongoDB collection!”;
?>

Now fire up your browser and launch the page. If all goes well you should see
“Done! Please, check your MongoDB collection!”

After running this script check your Mongo db collection, in that you can see your Mysql Table. However we haven’t done it on a large system, we are planning to do the same on a huge Postgres Sql system soon.

Openstack Cloud Software

Wednesday, October 17th, 2012 | Posted in Cloud computing

OpenStack : The Mission

“ To produce the ubiquitous Open Source Cloud Computing platform that will meet the needs of public and private cloud providers regardless of size, by being simple to implement and massively scalable.”

OpenStack is a collection of open source software projects that enterprises/service providers can use to setup and run their cloud compute and storage infrastructure.Rackspace and NASA are the key initial contributors to the stack. Rackspace contributed their “Cloud Files” platform (code) to power the Object Storage part of the OpenStack, while NASA contributed their “Nebula” platform (code) to power the Compute part. OpenStack consortium has managed to have more than 150 members including Canonical, Dell, Citrix etc.

There are 5 main service families under OpenStack

• Nova – Compute Service

• Swift – Storage Service

• Glance – Imaging Service

• Keystone – Identity Service

• Horizon – UI Service

Open Stack Compute Infrastructure (Nova)

Nova is the Computing Fabric controller for the OpenStack Cloud. All activities needed to support the life cycle of instances within the OpenStack cloud are handled by Nova. This makes Nova a Management Platform that manages compute resources, networking, authorization, and scalability needs of the OpenStack cloud. But, Nova does not provide any virtualization capabilities by itself; instead, it uses libvirt API to interact with supported hypervisors. Nova exposes all its capabilities through a web services API that is compatible with the EC2 API of Amazon Web Services.

Functions and Features:

• Instance life cycle management

• Management of compute resources

• Networking and Authorization

• REST-based API

• Asynchronous eventually consistent communication

• Hypervisor agnostic : support for Xen, XenServer/XCP, KVM, UML, VMware vSphere and Hyper-V

OpenStack Storage Infrastructure (Swift)

Swift provides a distributed, eventually consistent virtual object store for OpenStack. It is analogous to Amazon Web Services – Simple Storage Service (S3). Swift is capable of storing billions of objects distributed across nodes. Swift has built-in redundancy and fail-over management and is capable of archiving and media streaming. It is extremely scalable in terms of both size (several petabytes) and capacity (number of objects).

Functions and Features

• Storage of large number of objects

• Storage of large sized objects

• Data Redundancy

• Archival capabilities – Work with large datasets

• Data container for virtual machines and cloud apps

• Media Streaming capabilities

• Secure storage of objects

• Backup and archival

• Extreme scalability

OpenStack Imaging Service (Glance)

OpenStack Imaging Service is a lookup and retrieval system for virtual machine images. It can be configured to use any one of the following storage backends:

• Local filesystem (default)

• OpenStack Object Store to store images

• S3 storage directly

• S3 storage with Object Store as the intermediate for S3 access.

• HTTP (read-only)

Functions and Features

• Provides imaging service

OpenStack Identity Service (Keystone)

Keystone provides identity and access policy services for all components in the OpenStack family. It implements it’s own REST based API (Identity API). It provides authentication and authorization for all components of OpenStack including (but not limited to) Swift, Glance, Nova. Authentication verifies that a request actually comes from who it says it does. Authorization is verifying whether the authenticated user has access to the services he/she is requesting for.

Keystone provides two ways of authentication. One is username/password based and the other is token based. Apart from that, keystone provides the following services:

• Token Service (that carries authorization information about an authenticated user)

• Catalog Service (that contains a list of available services at the users’ disposal)

• Policy Service (that let’s keystone manage access to specific services by specific users or groups).

Openstack Administrative Web-Interface (Horizon)

Horizon the web based dashboard can be used to manage /administer OpenStack services. It can be used to manage instances and images, create keypairs, attach volumes to instances, manipulate Swift containers etc. Apart from this, dashboard even gives the user access to instance console and can connect to an instance through VNC. Overall, Horizon

Features the following:

• Instance Management – Create or terminate instance, view console logs and connect through VNC, Attaching volumes, etc.

• Access and Security Management – Create security groups, manage keypairs, assign floating IPs, etc.

• Flavor Management – Manage different flavors or instance virtual hardware templates.

• Image Management – Edit or delete images.

• View service catalog.

• Manage users, quotas and usage for projects.

• User Management – Create user, etc.

• Volume Management – Creating Volumes and snapshots.

• Object Store Manipulation – Create, delete containers and objects.

• Downloading environment variables for a project.

INSTALLATING OPEN STACK

We can install open stack ESSEX very easily using StackGeek script. Login to your box and install git with apt-get. We’ll become root and do an update first.

sudo su
apt-get update
apt-get install git

Now checkout the StackGeek scripts from Github:

git clone git://github.com/StackGeek/openstackgeek.git   
cd openstackgeek

Install the Base Scripts

Be sure to take a look at the scripts before you run them. Keep in mind the scripts will periodically prompt you for input, either for confirming installation of a package, or asking you for information for configuration.

Start the installation by running the first script:

./openstack_base_1.sh

When the script finishes you’ll see instructions for manually configuring your network. You can edit the interfaces file by doing a:

vim /etc/network/interfaces

Copy and paste the network code provided by the script into the file and then edit:

auto eth0 
iface eth0 inet static
  address 192.168.1.48		
  network 192.168.1.0		
  netmask 255.255.255.0
 broadcast 192.168.1.255
  gateway 192.168.1.124			
  dns-nameservers 8.8.8.8  
auto eth1

Change the settings for your network configuration and then restart networking and run the next script:

/etc/init.d/networking restart

Then run the second script :

./openstack_base_2.sh

After the second script finishes, you’ll need to set up a logical volume for Nova to use for creating snapshots and volumes. Nova is OpenStack’s compute controller process.

Here’s the output from the format and volume creation process:-

root@manager-System-Product-Name:/openstackgeek# fdisk /dev/sda
Device contains neither a valid DOS partition table,nor Sun,SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0xb39fe7af.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): n
Partition type:
   p   primary (0 primary, 0 extended, 4 free)
   e   extended
Select (default p): p Partition number (1-4, default 1): 3  
First sector (2048-62914559, default 2048): 
 Using default value 2048 Last sector,(2048-62914559,default 62914559): 
Using default value 62914559 
Command (m for help): w The partition table has been altered! 
Calling ioctl() to re-read partition table. Syncing disks.
root@manager-System-Product-Name:/openstackgeek# pvcreate -ff /dev/sda3
 Physical volume "/dev/sda3" successfully created
root@manager-System-Product-Name:/openstackgeek# vgcreate nova-volumes /dev/sda3
 Volume group "nova-volumes" successfully created

Note: Your device names may vary.

Installing MySql

The OpenStack components use MySQL for storing state information. Start the install script for MySQL by entering the following:

./openstack_mysql.sh

You’ll be prompted for a password used for each of the components to talk to MySQL:
Enter a password to be used for the OpenStack services
to talk to MySQL (users nova, glance, keystone): redhat
Note(Here “redhat” is the password given to nova,glance,keystone)

During the installation process you will be prompted for a root password for MySQL. In our install example we use the same password, ‘redhat’. At the end of the MySQL install you’ll be prompted for your root password again.

mysql start/running, process 8796
################################################################################ 
Creating OpenStack databases and users. 
Use your database password when prompted. 
 Run './openstack_keystone.sh' when the script exits. 
################################################################################
Enter password:
After MySQL is running, you should be able to login with any of the OpenStack 
users and/or the root admin account by doing the following:

mysql -u root -predhat
mysql -u nova -predhat nova
mysql -u keystone -predhat keystone
mysql -u glance -predhat glance

Installing Keystone

Keystone is OpenStack’s identity manager. Start the install of Keystone by doing:

./openstack_keystone.sh

You’ll be prompted for a token, the password you entered for OpenStack’s services, and your email address. The email address is used to populate the user’s information in the database.

Enter a token for the OpenStack services to auth wth keystone: redhattoken 
Enter the password you used for the MySQL users (nova, glance, keystone):redhat 
Enter the email address for accounts(nova,glance,keystone):user@company.com
You should be able to query Keystone at this point. 
You’ll need to source the“stackrc” file before you talk to Keystone:
 . ./stackrc   
 keystone user-list    
 Keystone should return a list of users:
+----------------------------------+---------+------------------------+--------+
|                id                | enabled |         email          |  name  |
+----------------------------------+---------+------------------------+--------+
| b32b9017fb954eeeacb10bebf14aceb3 | True    | user@company.com       | demo   |
| bfcbaa1425ae4cd2b8ff1ddcf95c907a | True    | user@company.com       | glance |
| c1ca1604c38443f2856e3818c4ceb4d4 | True    | user@company.com       | nova   |
| dd183fe2daac436682e0550d3c339dde | True    | user@company.com       | admin  |
+----------------------------------+---------+------------------------+--------+

Installing Glance

Glance is OpenStack’s image manager. Start the install of Glance by doing:

./openstack_glance.sh

The script will download an Ubuntu 12.04 LTS cloud image from StackGeek’s S3 bucket.Once it’s done, you should be able to get a list of images:

glance index

Here’s the expected output:

ID              :- 71b8b5d5-a972-48b3-b940-98a74b85ed6a 
Name            :- Ubuntu 12.04 LTS
Disk Format     :- qcow2 
Container Format:- ovf 
Size            :- 226426880

Installing Nova

We’re almost done installing! The last component is the most important one as well. Nova is OpenStack’s compute and network manager. It’s responsible for starting instances, creating snapshots and volumes, and managing the network. Start the Nova install by doing:

./openstack_nova.sh

You’ll immediately be prompted for a few items, including your existing network interface’s IP address, the fixed network address, and the floating pool addresses:

######################################################
The IP address for eth0 is probably 192.168.1.48.
Keep in mind you need an eth1 for this to work.
######################################################
Enter the primary ethernet interface IP: 192.168.1.48
Enter the fixed network (eg. 10.0.2.32/27): 192.168.1.0/24
Enter the fixed starting IP (eg. 10.0.2.33): 192.168.1.1
############################################################################
The floating range can be a subset of your current network. 
Configure your DHCP server to block out the range before you choose it here. 
An example would be 10.0.1.224-255
############################################################################
Enter the floating network (eg. 10.0.1.224/27):  
Enter the floating netowrk size (eg. 32):

The fixed network is a set of IP addresses which will be local to the compute nodes. Think of these addresses as being held and routed internally inside any of the compute node instances.

The floating network is a pool of addresses which can be assigned to the instances you are running. For example, you could start a web server and map an external IP to it for serving a site on the Internet.

Finish Installing Nova

Nova should finish installing after you enter all the network information. When it’s done, you should be able to get a list of images from Glance via Nova:

 nova image-list

And get the expected output we saw earlier from Glance:

root@manager-System-Product-Name:/openstackgeek# nova image-list
+--------------------------------------+------------------+--------+--------+
|                  ID                  |       Name       | Status | Server |
+--------------------------------------+------------------+--------+--------+
| 71b8b5d5-a972-48b3-b940-98a74b85ed6a | Ubuntu 12.04 LTS | ACTIVE |        |
+--------------------------------------+------------------+--------+--------+

Installing Horizon

Horizon is the UI and dashboard controller for OpenStack. Install it by doing:

./openstack_horizon.sh

When it’s done installing, you’ll be given a URL to access the dashboard. 
You’ll be able to login with the user ‘admin’ 
and whatever you entered earlier for your password. 
If you’ve forgotten it, simply grep for it in your environment:

env |grep OS_PASSWORD

The URL will be : http://192.168.1.48

You can login the Openstack dashboard by the following credentials

USER : admin

PASSWORD : redhat

MySQL Optimization

Friday, December 10th, 2010 | Posted in MySQL

Database optimization is the process of configuring database to use system resource efficiently and perform tasks quickly. To optimize mysql you should know the work flow of entire system, your hardware, operating system, disk I/O performance etc.
Why to Optimize
You can do more with less. The default mysql setup is optimized for a minimal system because it should work well on a minimal hardware. But when you use a dedicated mysql server with high traffic and complex queries you have to optimize mysql.
MySQL Server tuning Considerations
Here you will find some common optimization parameters.

MySQL variables
Hardware
Disk
Application

MySQL Optimization
MySQL global variables don’t have any predefined optimum values. It is a trial and monitor process. It depends on all the above parameters. Here you will see some of the common parameters.
Key-buffer-size
It is size of the buffer used to index blocks for MyISAM tables. On a dedicated mysql server with MyISAM storage engine 25-30% of systems total memory you can allocate for key_buffer_size. To fine tune key_buffer_size you can compare the variables key_reads and the key_read_requests.
This ratio should be at least 1:100.

SHOW STATUS LIKE ‘%key_read%’;
+——————-+————-+
| Variable_name | Value |
+——————-+————-+
| Key_read_requests | 10726813161 |
| Key_reads | 92790146 |
+——————-+————-+
Here the ratio is 1:115 which is acceptable.
But suppose you get a ratio 1: 10 then you need to add more key buffer and upgrade hardware accordingly.
Query Cache
“My website is too slow while loading dynamic pages”. If it is a mysql database related issue, following MySQL variables will be your solution.
query_cache_type
Set the query cache type. There are 3 values 0 ,1 or 2

0	Do not cache any query result
1	Cache query results.
2	Cache results ondemand. Cacheable queries that begin with SELECT SQL_CACHE.

query_cache_size
The amount of memory used to cache query result. Default is 0 which disable query cache.
The optimum value is depend on your application.
query_cache_limit
Do not cache results that are larger than this number of bytes. The default value is 1MB.
Status checking
SHOW STATUS LIKE ‘%qcache%’;
+————————-+———-+
| Variable_name | Value |
+————————-+———-+
| Qcache_free_blocks | 1 |
| Qcache_free_memory | 8371272 |
| Qcache_hits | 23547551 |
| Qcache_inserts | 46909131 |
| Qcache_lowmem_prunes | 5110536 |
| Qcache_not_cached | 2760196 |
| Qcache_queries_in_cache | 0 |
| Qcache_total_blocks | 1 |
+————————-+———-+
There were 46909131 queries and out which 23547551 queries cached and remaining not cached. Here the issue will either the result is greater than query_cache_limit or greater than query_cache_size itself. You have to trial and monitor 🙂
Qcache_lowmem_prunes.
When a query is removed from the query cache, this value will be incremented. If it increases quickly, and you still have memory to spare, you can set query_cache_size high, If it never increases, you can reduce the cache size.

sort_buffer
The sort_buffer is a useful for speed up myisamchk operations. It can also be useful when performing large numbers of sorts.

tmp_table_size

This variable determines the maximum size for a temporary table in memory. The maximum in memory size is minimum of tmp_table_size and max_heap_table_size. You can compare
Created_tmp_disk_tables and Created_tmp_tables to optimize tmp_table_size.

innodb_buffer_pool_size

This variable is target for innodb table and it is similar to key_buffer_size in MyISAM table.
On a dedicated mysql server using innodb you can set this upto 80% of RAM.
Hardware for mysql
If you have large tables(>3GB), you should consider 64 bit hardware as mysql uses a lots of 64bit integers internally.

You need more memory(RAM) if you want mysql to handle large number of connections simultaneously. More RAM will speed up key updates by keeping most of the pages in RAM

Another consideration is Ethernet device, You can use a 1G Ethernet for a dedicated mysql server for fast remote connections.

Disk performance is also an important parameter.
Disk Optimization
Striping disk (RAID 0) will increase both read and write throughput.

Don’t use RAID 1 or mirroring on disk for temporary files.

On Linux, mount the disks with async (default) and noatime.
Optimizing your application
Cache process in your application

Specify the column name in queries(eg dont use SELECT * FROM……)

Use persistent connections

USE EXPLAIN to explain!!.You will see detail below.

Queries and Indexes

Let us start with a simple query SELECT firstname FROM student WHERE id=’145870′;
MySQL start searching from the beginning row to find the student with id 145870. It does not even know it exist or not. An index is a sorted file which have an entry for each row.MySQL can find the corresponding record very quickly by referring this index.
EXPLAIN is a nice tool to understand your queries

EXPLAIN SELECT firstname,lastname FROM student WHERE id=’145870′;

There are many more optimization variables and indxing methods. It is difficult include everything in a single article. But you can start mysql fine tuning while you database is underperfoming.

Deploying a load balanced e-commerce portal in Amazon EC2

Wednesday, June 9th, 2010 | Posted in Cloud computing

Update: NFS should not be used as that will be a SPOF. One should use S3 or other object stores. An alternative could be multi-node GlusterFS if someone needs volumes shared across nodes.

When building an infrastructure for an eCommerce portal on Cloud, it is important to note that it should be available all the time, that it is fail safe with outages like the one we had recently in AWS EU and U.S. East Regions, survive Hardware failure or any other issues like bug in the system or deployment errors. We built an infrastructure on AWS Cloud that address all these issues with LAMP using various AWS Cloud services like EC2, S3, RDS, EBS etc. It is described in detail below:

Achieving High Availability & Fail over across Datacenters

Elastic Load Balancer (ELB)

The Elastic Loadbalancer ( ELB ) service provided by AWS tries to achieve the following:

(i) Spans across Datacenters: Loadbalance traffic across mulitple datacenters (AZ )thus providing high availability even if one datacenter goes down. So you should always make sure that when you launch instances under an ELB, you should launch it in different Availability zones. You can also launch instances in the same AZ but by default ELB will redirect request across multiple AZ in a Round Robin way.

(ii) Failover: ELB will periodically monitor the health of the instances and if any of the instance or monitored service ( e.g. Http ) goes down, ELB will stop redirecting requests to that instance and all the request will be redirected to the remaining number of instances registered under ELB. When the instance comes backup, it will again start redirecting requests to that instance.

(iii) Handling root domain ( apex / main domain ) and subdomains: ELB can loadbalance only those requests coming to alias / subdomain( www ). It cannot handle request coming to root domain. This is because when you configure DNS for enabling ELB, you can only set CNAME to ELB for subdomains. There are 2 reasons for this. One is when you configure ELB, you will only get a Public DNS name for the ELB like the following instead of a Public IP.

[bash]Test-1736333854.us-east-1.elb.amazonaws.com [/bash]

This is because AWS changes the Public IP of the ELB periodically for providing scalability for ELB itself. Another reason why you cannot redirect main domain request to ELB is that DNS protocol itself restricts the usage of CNAME or anything other than “A” record for a root domain. So you cannot CNAME root domain to ELB DNS name.

So for serving root domain requests with ELB , there are only work arounds like mentioned below:

a) We have to assign an elastic IP for an instance under ELB. But what if this instance goes down? Set heartbeat to switch EIP? This is a bit complicated setup as switching EIP to instances present across AZ takes time.

b)The other option is to have the root domain point to the IP addresses of the destination by configuring one or more “A” records (address records) for root domain. You can do that if you know the destination IP addresses are fixed, such as if you are using EC2 Elastic IP addresses. We wouldn’t recommend this because IP addresses will be cached at the client end for long time even if you set low value of TTL at the nameservers. This is because TTL value can also be configured at the the client end overriding the TTL value provided by the nameserver of the domain. e.g. with nscd ( Nameserver Caching Daemon) you can set the TTL value manually in its configuration file.

c) You can keep a separate web server not under ELB with a Redirect Rule for redirecting root domain requests to www. You should make sure that this webserver is highly available as well.

d) A better solution is to go for Domain Registrars ( DNS service providers ) who provide this feature of redirecting root domain requests to www. So this can be handled at the DNS itself. The DNS service provided by AWS “Route53” can be used for this ‘Zone apex’ ( root domain ) redirection.

(iv) SSL Termination

There is support for “SSL termination” in ELB which means you can use ELB to loadbalance HTTPS requests too. You just need to buy the SSL certificate and simply upload it to ELB. ELB will redirect all the HTTPS request to the backend servers. So you can make an eCommerce portal highly secure and highly available with ELB.

(v) Persistent Session

You can enable Sticky Session with ELB but the problem is users will be logged out if any of the instance / webserver goes down and ELB will redirect the subsequent requests from the same user to a different instance and it will prompt the user to login again. To tackle this there were few options we had considered –
a)You can either setup distributed failover memcached server or
b)You can use RDS for storing Session.

We went for RDS as our Session Management store since RDS is an excellent choice for Database Administration as well if you are using MySQL as the Database.

Your application must be configured to write session data to an RDS database. So when an instance / webserver goes down and when the ELB redirects the user request to a different instance, the user will not be asked to login again as all servers are reading session data from the same place that is RDS. The user won’t notice anything at all, even though they’ve now started talking to another server. We recommend using a Multi-AZ RDS instance and write session data into this. So if one of your EC2 instances goes down, the other instances will still have access to the RDS database, and likewise if an RDS zone goes down, Amazon fail this over to the second AZ internally, transparently to you and your application.

So the easiest and most reliable way to share sessions for failover on a multi-server environment is to use RDS, since Amazon handle the database layer’s failover for you.

So basically you can achieve two things by using RDS – Session management and Database Management.

AutoScaling

The Autoscaling service provided by AWS allows you to scale horizontally up / down with CPU usage, RAM, Disk I/O etc.

Ideally you should use a Base AMI with Autoscaling that will pull the required packages from a Centralized location like Chef Platform and code from the Version Control System or S3. You can write a startup script to run on instance bootup for this purpose. So when Autoscaling launches a new instance it will pull all the latest updated versions of the packages, code and also any other required custom configurations from a centralized location. This will also make it easier to manage all the configuration details, code updates from a centralized location using tools like Chef Platform, Version Control System or S3 respectively.

Apart from Centralised Configuration / Code management, the reason for using Base ami with Autoscaling is that it is not possible to change the ami configured with Autoscaling service dynamically.

Storage for Application Files

We came across lot of options for storing the application files. However you have to consider your priorities before you select a storage service for the code. Following are the points to consider for your application file storage system:

(i)Latency issues: All shared storage systems like NFS / GlusterFS / EBS / S3 etc have latency issues when compared to Instance store (Ephemeral Storage)

(ii)High availability: If you are using a shared storage service like NFS, it should never go down for the entire system to be available all the time.

(iii)Access to the code: How to get the latest code during incremental roll out of a new instance because if you are using a shared storage, it becomes difficult to gives access to the shared storage system when a new instance is launched

We went for instance store / ephemeral store that gives you better I/O performance. You can keep your own highly available SVN repository or go for publicly available Version Control Systems like GitHub. At the same time you can also keep a copy in S3 and sync to it whenever there is a code update. This will make it more redundant.

The problem with using shared storage service like NFS / GlusterFS with EBS / S3 is it becomes difficult to avoid single point failure for NFS / GlusterFS service. But if your site doesn’t have much hits and your priority becomes redundancy, you can go for mounting S3 as filesystem using tools like s3cmd and use that as a shared storage with NFS for multiple instance. The problem with S3 is that it is not intended to be used as a filesystem and there have been issues reported with speed and caching. Or you can use EBS volume for code storage if you have only a single instance serving the request. Even using NFS with EBS volumes ( with frequent snapshots to S3 ) gives better performance than using S3 as shared storage for files.

Not only does instance store gives you better performance, error rates very rare. with EBS volumes error rates are reported frequently. Recent outages with AWS EU & US East Regions shows that the down time was made worse due to increase in time taken to recover from EBS errors.

Code Deployment

For automating code deployment, you can configure deployment tools like Capistrano. This will become very handy when you have multiple servers to update simultaneously. Capistrano uses Ruby language and is built for Ruby code deployment but with little changes, you can automate deployment of PHP / Perl / Python / JAVA based application.

chef-deploy is another tool that comes with chef for automating code deployment. Continuous Integration tools like Hudson / Cruise Control are excellent tools when you want to automate the Build, Deployment, Test and Rollback process.

For code deployment, we follow a Release Management process where we keep a staging environment that is an exact replica of the production environment. We push code to the production environment only when it’s been completely tested in the staging environment and approved by the Release Manager. This will further reduce the errors / bugs / and downtime time caused due to the code release.

Database Server

We went for RDS across AZ for High availability. AWS will take care of Redundancy, Performance Optimisation, Scalability and Backup. You can avoid the hassle of managing a Database Server by using RDS. RDS is as an excellent distributed highly available Session Management System. You can also take regular backup from RDS and keep it in S3.

You can also use Master–Slave Replication setup instead of RDS. This is also a good option for achieving high availability for Database server. The challenging part will be to manually configure failover for both master and slave servers, achieving scalability with traffic, backup configuration and performance optimization with increasing load. With RDS, all these will be managed by AWS.

Log handling

Keep all the important logs like Application logs, Syslogs, SSH log etc in EBS volume. You can either schedule regular snapshots of these EBS volume to S3 or you can even sync these log files to an S3 bucket periodically using tools like s3sync.

Configuration Management

If you have more than one server or are planning to scale up in future or would like to automate a lot of administration / coding stuffs, you should definitely use one of the Open Source freely available Configuration Management tools like Chef / puppet / Cfengine

Chef is new and has default support for AWS / EC2. We use Chef extensively for managing our infrastructure in AWS. Chef provide a lot of readily available cookbooks ( recipes / roles ) for LAMP, JAVA app, Cassandra, Hadoop, Nagios etc which can be used readily ( or with minimum customization ) to automate the infrastructure setup and configuration. Chef also comes with a tool called Chef-deploy for automating deployment of code.

So using Chef along with tools like Hudson / Cruisecontrol, you can automate the entire setup from infrastructure setup to configuration management to building, deployment and testing of your application.

Performance

To improve performance you can implement the following:

(i)Use caching mechanisms like Memcache(DB scaling) / aiCache / Varnish.

(ii)CDN ( Content Delivery Network ) is a must if you want to provide better end-user response time. There are lot of CDN providers but we recommend AWS CloudFront or Akamai for serving static files and images. For start-up and small business, CDN might be costly but as your target audience grows larger and becomes more global, a CDN is necessary to achieve fast response times.

Monitoring & Alert

For monitoring, go for open source monitoring tools along with a SaaS based monitoring application.

(i)There are lot of free and open source option available in the market – Nagios, Zenoss,Zabbix etc. This can be automated with Chef in such a way that when a new server is launched in to the cluster, it will be automatically added to the Nagios list of monitored servers.

(ii)You can also use excellent SaaS based monitoring apps like Pingdom, mon.itor.us, site24x7.com etc for monitoring and alerting via email, SMS or Twitter.

(iii)Custom scripts or tools like Munin & Monit for monitoring and restarting services if it crashes.

Backup

You can keep copies of code in an S3 Bucket and sync it with tools like s3sync with every update. For DB Backup, in addition to automated RDS Backup, you can take periodical standard DB backups using mysqldump and store it in S3 bucket.You can also use EBS volumes for keeping replica of code and DB Backup with periodical snapshots to S3.

An important thing to note about S3 storage is it is only a Highly available Storage System. It is not backed up automatically. That means if you delete anything manually from s3, it will be forever gone unless you have manually backed it up with multiple copies in S3. So make sure that you have enough backups available in S3.

Migrate to Cloud

Posts Tagged ‘Company: MySQL AB’

Apache on the Cloud – The things you should know

PHP Caching : The way to speed up PHP sites.

APC

Memcached

Varnish – Cache

Where not to use Caching

Migrate Mysql database to Mongodb

MySQL Optimization

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Cloud based Voip solution enjoying 50% increase in performance

PostgreSQL migration to Amazon EC2

Cpanel migration to the cloud

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