Hyper-V Storage QoS behaviour

Question

Hi Together

I have a Hyper-V Storage QoS Policy (Dedicated) configured and applied to a VM with several disks attached -> same Policy applied to all disks of this VM.

My QoS Policy Limit: Max IOPS 50'000, Min IOPS 0

For the sake of clarity: Which mean that every disk has the possibility to use IOPS till Max value is reached -> because it's a dedicated Policy and underlaying Storage with Cluster Shared Volumes has engough Performance to compete.

Now my question: What is the exact behaviour when all disks are placed on the same CSV?

Get every disk still the promised performance through QoS Policy?

Thank you for Feedback.

Thread source link: https://social.technet.microsoft.com/Forums/windowsserver/en-US/08482107-2279-4e2a-8c02-6a5e34b0153e/hyperv-storage-qos-behaviour?forum=winserverhyperv

Answer 1

Hi SteveKeller,

Thanks for your clarification!

You are correct, Storage QoS are for VHD/VHDX based or VM based.

How does it works if your gonna apply different QoS Policies for different VHDX Files to the same VM?

According to the article, it seems dedicated policy applies to dedicated VHD or VM.

For example, if dedicated policy 1 applied to VHDX 1 on VM with Mini 100 IOPS ~ MAX 300 IOPS, policy 2 applied to VHDX 2 on VM with Mini 200 IOPS ~ 400 IOPS. Then the VM can have MAX 300 + 400 IOPS.

What is the exect behaviour if a VM has multiple VHDX Disks and these are separeted on different CSVs? (with dedicated QoS Policy)

What when all VHDX Disks are on the same CSV? (with dedicated QoS Policy)

As far as I'm concerned, it's no matter where the VHDX disks located in the same or different CSVs.

Thanks for your time!

Best Regards,