View source for Winter 2010 Presentations/Storage Performance

=Title=

Storage Performance
By: David Chisholm (dmchisho@learn.senecac.on.ca)

=Introduction=

In order to have our Koji Build Farm run as efficiently as possible we needed to find out which form of data storage would be the fastest overall. The candidates were:

* PATA Hard Drive connected via USB
* NFS share from HongKong
* iSCSI network connection to HongKong

===What results are we interested in?===

There are 3 main results that we are interested in when rating storage performance.

1. Read: The amount of data that can be read from the storage medium per second.
<br>
2. Write: The amount of data that can be written to the storage medium per second.
<br>
3. Access: Time required for a computer to process data from the processor and then retrieve the required data from a storage medium.

===Cost===

Since NFS and iSCSI are both network storage solutions they have no cost in themselves, but rely on network storage on a remote server. This price is simply the cost of the drives that will be installed in the remote storage server. A USB connected PATA or SATA drive requires both a hard drive and a PATA/SATA to USB interface such as an external drive enclosure.

* NFS: Free (Uses existing storage)
* iSCSI: Free (Uses existing storage)
* USB PATA: ~$100 CAD

===Pictures===
http://david-chisholm.no-ip.org/networkdiagram.jpg
<br>
http://www.paladinretrieval.net/hard%20drive.jpg

=Approach=

===How did we conduct our testing?===

*Benchmark using a linux untiliy called Bonnie++ written by Russell Coker.
*The Benchmark was run 3 times on each medium, the results were then averaged together.
*The command used is as follows:
 
 bonnie++ -d <location> -s 2048 -u root

===Pictures===
http://david-chisholm.no-ip.org/bonnie.jpg

=Process=

===What was the process we used to choose our benchmarking solution?===

The goal was to find a storage solution that would result in the best build times while using the most efficient use of the storage resources available to us.

The main issue encountered was finding a repeatable benchmarking solution what would give the desired results while being able to test all 3 of our storage mediums.

Common Linux tools such as the '''DD''' and '''HDPARM''' commands are capable of doing disk benchmarking, but will only work for physical devices and not network networked ones, making them useless tests for our purposes.

The solution was '''Bonnie++''', a Linux command line utility which gives an extensive amount amount of storage performance information while also having the ability to test all of our storage systems.

=Discovery=

We discovered that finding a viable benchmarking solution is harder then it sounds. Raw data will not always correspond with real results as it comes down to the application using those resources. This is evident in the mock tests using NFS vs USB PATA where USB PATA performed faster even though its benchmark results were lower using Bonnie++.

=Issues=

===USB PATA===
*Works without issue.

===NFS===
*Works, but results in longer build times than USB PATA even though it benchmarked at higher speeds.

===iSCSI===
*Seems to work at first, but only to a point.
*We can login to an initiator, however, under heavy load the target receives invalid opcodes, causing the connection to fail.
*Experimenting with a alignment value of 3 did not clear the issue.
*Using the exact same target with a F12 x86_64 initiator is successful, issue seems to be ARM related.

===Pictures===

http://exportabel.files.wordpress.com/2009/10/train_wreck_at_montparnasse_1895.jpg

=Bonnie++ Results=

==Write==
<table border="1" cellspacing="1" width="0">

<tr>
<th></th>
<th>Transfer Speed</th>
<th>Percentage Increase</th>
<th>CPU Usage</th>
</tr>

<tr>
<td align="center">PATA</td>
<td align="center">28,790 KB/s</td>
<td align="center">0%</td>
<td align="center">24%</td>

</tr>
<tr>
<td align="center">NFS</td>
<td align="center">43,363 KB/s</td>
<td align="center">50%</td>
<td align="center">16%</td>
</tr>

<tr>
<td align="center">iSCSI</td>
<td align="center">31,503 KB/s</td>
<td align="center">9%</td>
<td align="center">30%</td>
</tr>

</table>

==Read==
<table border="1" cellspacing="1" width="0%">

<tr>
<th></th>
<th>Transfer Speed</th>
<th>Percentage Increase</th>
<th>CPU Usage</th>
</tr>

<tr>
<td align="center">PATA</td>
<td align="center">25,991 KB/s</td>
<td align="center">0%</td>
<td align="center">10%</td>
</tr>

<tr>
<td align="center">NFS</td>
<td align="center">51,789 KB/s</td>
<td align="center">99%</td>
<td align="center">85%</td>

</tr>
<tr>
<td align="center">iSCSI</td>
<td align="center">59,147 KB/s</td>
<td align="center">127%</td>
<td align="center">84%</td>
</tr>

</table>

==Access==
<table border="1" cellspacing="1" width="0%">

<tr>
<th></th>
<th>Access (per second)</th>
<th>Percentage Increase</th>
<th>CPU Usage</th>

</tr>

<tr>
<td align="center">PATA</td>
<td align="center">121</td>
<td align="center">0%</td>
<td align="center">0%</td>

</tr>

<tr>
<td align="center">NFS</td>
<td align="center">1201</td>
<td align="center">1000%</td>
<td align="center">35%</td>

</tr>

<tr>
<td align="center">iSCSI</td>
<td align="center">2514</td>
<td align="center">2077%</td>
<td align="center">44%</td>

</tr>

</table>

=Links=
* Access Time - http://en.wikipedia.org/wiki/Access_time
* cDOT iSCSI - http://zenit.senecac.on.ca/wiki/index.php/Fedora_ARM_Secondary_Architecture/iSCSI