topic Re: Defrag for Windows 2012 R2 Hyper-V CSV volume in Array Performance and Data Protection

Defrag for Windows 2012 R2 Hyper-V CSV volume

Dave Baddorf — Wed, 13 Jan 2016 20:48:41 GMT

My Nimble customers have Cluster Shared Volumes (CSV) and run Windows 2012 R2 Hyper-V VM's on those CSV's. My question is should I run Windows Defrag on the VM's? And should I run Windows Defrag on the CSV volumes? Running a defrag analyze on a CSV volume can be done (see http://blogs.msdn.com/b/clustering/archive/2014/01/02/10486462.aspx) but I am not seeing the output that I've been accustomed to - I don't see a message about "you should/shouldn't defragment this volume" but rather just see messages about Slab Consolidation. Apparently Windows defrag works differently when the volume is thinly provisioned. But I can't seem to find very clear information on the best practices of defragrmenting a CSV volume which is thin provisioned. Which leads me to my above questions: Should I run defrag at the VM level? And should I run it on the CSV volume?

I appreciate any insight that anyone has to offer...

Thanks! Dave

Re: Defrag for Windows 2012 R2 Hyper-V CSV volume

Nick_Dyer — Thu, 14 Jan 2016 09:56:58 GMT

Hi Dave,

Wherever possible it's advisable NOT to run any defragmentation tools on a Nimble Storage platform. The CASL architecture has a built in defrag tool as part of it's garbage collection process (called sweeping) and is an always-on process running in the background of the file system; running a host-side defrag tool will merely change the layout of the blocks within the CASL architecture, leading to potentially worse performance overall.

Re: Defrag for Windows 2012 R2 Hyper-V CSV volume

Dave Baddorf — Tue, 19 Jan 2016 15:43:08 GMT

Thanks for your response, Nick! I just have one clarification on your response: When you said that you shouldn't run a Defrag on a Nimble Storage platform I'm assuming that you mean you shouldn't run Defrag on a Windows Hyper-V Host using the Nimble SAN as a Clustered Shared Volume (CSV). But does your recommendation also include not running a Defrag within the Windows VM's running on the Hyper-V Host? In other words, do you recommend not running Defrag on either the host nor the VM's? Thanks for your help!

Dave

Re: Defrag for Windows 2012 R2 Hyper-V CSV volume

Dave Baddorf — Wed, 27 Jan 2016 19:05:54 GMT

Does anyone have any comment on whether it is a good idea to defrag a Windows VM when running the guest on a Hypervisor which is storing the VM's on a Nimble SAN? I realize that I don't want to run defrag on a Windows Host, but how about within a VM?

Re: Defrag for Windows 2012 R2 Hyper-V CSV volume

Nick_Dyer — Wed, 27 Jan 2016 19:09:47 GMT

It is not recommended to run host-side defrag on any operating system, physical or virtual.