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Monday
Dec282009

VMware boot storm on NetApp - Part 2

I have received a few questions relating to my previous post about NetApp VMware bootstorm results and want to answer them here.  I have also had a chance to look through the performance data gathered during the tests and have a few interesting data points to share. I also wanted to mention that I now have a pair of second generation Performance Accelerator Modules (PAM 2) in hand and will be publishing updated VMware boot storm results with the larger capacity cards.

What type of disk were the virtual machines stored on?

  • The virtual machines were stored on a SATA RAID-DP aggregate.


What was the rate of data reduction through deduplication?

  • The VMDK files were all fully provisioned at the time of creation. Each operating system type was placed on a different NFS datastore. This resulted in 50 virtual machines on each of 4 shares. The deduplication reduced the physical footprint of the data by 97%


A few interesting stats gathered during the testing. These numbers are not exact and due to the somewhat imprecise nature of starting and stopping statit in synchronization with the start and end of each test.


  • The CPU utilization moved inversely with the boot time. The shorter the boot time, the higher the CPU utilization. This is not surprising as during the faster boots, the CPUs were not waiting around for disk drives to respond. More data was served from cache the the CPU could stay more utilized.
  • The total NFS operations required for each test was 2.8 million.
  • The total GB read by the VMware physical servers from the NetApp was roughly 49GB.
  • The total GB read from disk trended down between cold and warm cache boots. This is what I expected and would be somewhat concerned if it was not true.
  • The total GB read from disk trended down with the addition of each PAM. Again, I would be somewhat concerned if this was not the case.
  • The total GB read from disk took a significant drop when the data was deduplicated. This helps to prove out the theory that NetApp is no longer going to disk for every read of a different logical block that points to the same physical block.


How much disk load was eliminated by the combination of dedup and PAM?

  • The cold boots with no dedup and no PAM read about 67GB of data from disk. The cold boot with dedup and no PAM dropped that down to around 16GB. Adding 2 PAM (or 32GB of extended dedup aware cache) dropped the amount of data read from disk to less that 4GB.

Originally posted at http://ctistrategy.com


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Reader Comments (2)

This is great data, what would be very interesting is if you could repeat this test with another storage vendors array and / or storage protocol.

February 11, 2010 | Unregistered CommenterVaughn Stewart

Vaughn,

Thanks for the comment. This started out as an exercise to measure the impact of PAM cards and dedup on the VMware environment. I am just about to wrap up my PAM II testing. Now that we have built the test harness, it would be interesting to test out iSCSI and FC as well. Let me see if I can pull that off.

- Jesse

February 12, 2010 | Unregistered CommenterJesse St. Laurent

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