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FAST Cache and VDI

In continuation to my earlier post on impact of  FAST Cache on database and Virtual Machine workloads , this post will show some statistics of FAST Cache on VDI workloads. VDI or Virtual Desktop infrastructure workloads are always challenging because of the components that construct them. OS drives and User Profile drives forms the major components with additional components varying from vendor to vendor like space used for Write Cache , Disposable disks , replica disks etc.. Typically OS Drives are from SAN device while the User Profiles are carved out of NAS. From my earlier experience with FAST Cache on SAN drives , I was pretty confident of a good performance from FAST Cache of my SAN components of the VDI infrastructure but was skeptical on the its performance for NAS workloads.FAST Cache can play a major role in enhancing the end-user experience by increasing the disk performance that constitutes VDI.

Below shown data on VDI and FAST Cache are from my experience and could vary based on the user load , components and how they are configured  but this post is to give a fair bit of idea on the performance of FAST Cache on VDI work environments. I would not be covering how FAST Cache can help during  Boot Storm since there are lot of posts already covering them.

First component is to see the performance of FAST Cache on Write Cache LUN. Shown below are the FAST Cache Hit ratio and response time of FAST Cache LUN.

Below shown graph indicates the performance of infrastructure LUN that constitutes the drive where OS drives are streamed and other infrastructure servers are hosted. Amazing response time of less than 2ms and FAST Cache utilization of 90% and above consistently.

Write Cache drive has a very good response time of less than 1 ms predominantly thanks to consistently high utilization of FAST Cache ( Greater than 85% throughout) as shown below.

Last but not the least the Performance of FAST Cache on NAS drives or the User profile drive where we could see 75% hit ratio for the FAST Cache . Remember NAS in itself spreads load across multiple drives for optimal performance and with FAST Cache it just got better.
Definitely , FAST Cache performs better for SAN work loads or block data than the file data or the NAS work loads but this result was an eye opener in terms amount of improvement that it could give for NAS work loads as well.
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Categories: Storage Tags: , , ,
  1. August 17, 2011 at 10:30 pm

    Hi There

    Are these figures based on a XenDesktop deployment with PVS and a write cache location on the SAN? I’m currently looking at this and was wondering about the FAST CACHE effectiveness

    • August 19, 2011 at 10:51 am

      Yes with all components except for User Drive on SAN .

  1. July 27, 2011 at 1:10 pm

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