Introduction

Iozone is an open source file system benchmarking tool which lets you to evaluate various aspects of a filesystem performance like read, write, rewrite, random read etc etc. It is ported to various platforms and can be run on all major operating systems like Linux, Microsoft Windows Mac OS X. Though it can be used for the detailed analysis of the filesytem IO performances, here we describe in short how to install it in Linux and get the analysis plotted to a graph.

How to install

1. Download the rpm source fro the Iozone from the following link or enter the follwing command at the command prompt

wget http://www.iozone.org/src/current/iozone-3-338.i386.rpm

2. install Iozone using the following command

rpm -ivh /path/to/iozone-3-338.i386.rpm

Now the filesystem benchmarking tool is installed. To verify the installation you can find the files of Iozone tool in the directory /opt/iozone/

Plotting a graph from Iozone analysis

For the plotting of a graph you should ensure that gnuplot is already installed in your machine. Gnuplot is a command-driven opensource function plotting tool. If it isn’t installed you may install it using the following command

yum install gnuplot

After ensuring that you have got gnuplot installed. Lets try plotting the analysis of the Iozone tool on a graph. Here we will analyze the filesystem with in auto mode. Run th iozone command and redirect its output to a file.

/opt/iozone/bin/iozone -a -g 4m > /tmp/test_analysis

In the above command we have set the maximum size of a file for auto mode  to 4mb with -g option. For brief study about Iozone commands use

/opt/iozone/bin/iozone -h

To generate the graph there is another command which is installed with the iozone tool ie Generate_Graphs. To plot the graph use the following commands

/opt/iozone/bin/Generate_Graphs /tmp/test_analysis

A new window will pop up with the plotted graph of the write performance. At the command line if you hit enter then new graph is plotted fro the rewrite performance. Thus there will be graph plotted for many IO performances as you hit enter each time. Evaluate the required IO performances from the set of graphs depending on the application that you are planning to deploy.

Have a nice day

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There are four important steps we should follow when it comes to the transfer of cPanel accounts among different server.

Below a simple and brief description is given on how to perform the migration.

Steps to transfer cPanel accounts

1. Change the $TTL of the zone in old server
2. Transfer the accounts.
3. Update the nameservers.
4. Change the A record of the zone file in old server

1. Change the $TTL of the zone in old server

Before one week of the scheduled transfer, all the $TTL values in the zone file must be changed to a smaller value between 30 minutes to 1 hour. This will take some time to propogate  to various ISPs around the world. The change in $TTL value ensures that the fresh zone files are loaded all around the world faster and that they access the old server for a shorter duration.

2. Transfer the accounts

Transfer the account using whm. If the size of the account is more than of 300 mb then move the folder which is of larger size to another directory outside that account. Then create a symbolic link for that folder in the original directory. After the transfer of the account using whm, scp the moved folder to the new server.

Also rsync the following directories between the two servers.

1. /var/cpanel
2. /usr/local/cpanel

3. Update the nameserver

Change the ip address of the child nameserver at the domain registrar. There will be a propogation delay of almost 48 hours.

4. Change the A record of the zone file in old server

For the time of propogation delay the domain keeps resoling to old server.  To make it resolve to new server, change the A record in the zone files of the old server.

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