ITEBlogThis article is part of a larger series on “Why Windows Server 2012 R2” where my peers and I detail many of the new features in Server 2012 R2 including step by step guides where appropriate. You can see the whole series here:
Windows Server 2012 R2 Launch Blog Series Index

Storage Quality of Service
Storage Quality of Service is a new feature in Windows Server 2012 R2 in the Hypervisor. It enables you to control a VMs use of disk IO so that you can manage a VMs performance relative to disk access. This is a very necessary ability if you wish to run multiple VMs and insure each VM has adequate access to the disk and that no single VM consumes all of the disk IO leaving the others to have poor performance.

The Storage Quality of Service is set on a per Virtual Machine basis. You can set a Maximum and a Minimum level. The Maximum sets a cap and the Minimum sets a reservation.

If you have the luxury of a San you could accomplish the same result of setting a Maximum cap by provisioning a Lun, for that VM’s drive, and then set a cap on that. This is how administrators would coral a poorly behaving application if they couldn’t get the business group to fix the app. You can see that it is much easier to set this limit on the VM rather than relying on your San to do the work. Further you can now set the limits no matter where the virtual disk is, no need for a San.

Step by Step
The only feature that needs to be installed is the Hyper-v Role in Server 2012 R2 and then have the ability to set limits on your IO. To do this on your VM, just follow the steps outline below:


  • Open the Settings on your VM. From Hyper-V Manager, Cluster Manager, or VMM
  • Select the VM and go into the “Settings”
  • Select the disk that you want to set the limits on.  (Works on both IDE and SCSI disks)
  • Expand the disk properties and choose “Advanced Features”
  • Click the checkbox to “Enable Quality of Service management”
  • Set your desired Maximum or Minimum
  • Click on “Apply” or “OK”

That is it. That is how easy it is to set Quality of Service limits on your Disk IO for your Virtual Machines! Stay tuned to the Windows Server 2012 R2 Launch Blog Series for more insight into the new features of Windows Server 2012 R2.