I/O throughput on VM System Disk

Hi all,

I've got a Generation 2 VM running Windows 2012R2 though SCVMM/Hyper-V 2012R2 (update roll-up 6).

The VM has two disks (C: and D: drive) on separate SCSI controllers, but with both VHDX's in the same folder on the same SMB3 share.

When I run DiskSPD on the C: drive, I get around 10K IOPS and 100MB/s throughput, when I run the same test on the D: drive I get 100K IOPS and 6Gbps throughput. Nothing else is using the SMB3 share to affect the results, and the tests have been run many times with the same result..

Any suggestions as to why that might be?

Many Thanks,

David

August 26th, 2015 11:04am

Hi David,

on separate SCSI controllers Does both this two disks have the same block size? If they are same block size, can you try to add another virtual SCSI controller and disk to this vm then perform the same test for compare with D drive.

You can refer the following article to know the details test process with DiskSPD.

DiskSpd, PowerShell and storage performance: measuring IOPs, throughput and latency for both local disks and SMB file shares

http://blogs.technet.com/b/josebda/archive/2014/10/13/diskspd-powershell-and-storage-performance-measuring-iops-throughput-and-latency-for-both-local-disks-and-smb-file-shares.aspx

Im glad to be of help to you!

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August 28th, 2015 2:51am

Hi,

are both disks fixed?

August 28th, 2015 2:59am

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