This blog post was originally written by Michael Schroeder, Thomas Cantwell and Aditi Satam.
Microsoft has added a number of new features and capabilities to Windows Server 2012R2, as well as updated many as well.
Dell PowerEdge servers, such as the Dell PowerEdge R620 and R720, support Windows Hyper-V, and Dell also offers the Hyper-V role installed (if selected during purchase) when a server has a factory-installed OS (http://en.community.dell.com/techcenter/b/techcenter/archive/2013/11/21/the-top-5-reasons-to-buy-a-dell-factory-installed-oem-operating-system-when-you-purchase-a-new-dell-server.aspx ).
Dell PowerEdge servers can take full advantage of these new capabilities. Storage QOS was developed to prevent any single VM or set of VMs from taking over all the storage bandwidth used by the VHDs in a server.
As you can see in the screen shot, under VM settings, you can select the Advanced Features option under hard drives to configure your storage QoS policy. Storage QoS is implemented on a per-virtual hard disk basis.
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Key benefits of Hyper-V Storage QOS:
- From a hosting perspective, QoS can be used to classify storage SLAs for different levels of performance. For example, gold, silver and bronze configurations for different classes of VM tenants.
- Storage QoS can prevent disruptive VMs from monopolizing the available storage capacity. This allows bandwidth available to the neighboring good citizen VMs.
- Allows you to send alerts when minimum IOPS have not been met for a virtual disk.
Control of:
- Minimum IOPS per virtual hard disk
- Maximum IOPS per virtual hard disk
Ability to manage via:
- Hyper-V Manager – see Advanced Features for each VHD when setting up the VM.
- PowerShell
Limitations:
- Works at the VHDX layer.
- Storage QoS is not available, if you are using shared virtual hard disks.
- Cannot enable storage QoS in conjunction with differencing VHDs when the parent and child disks are on separate volumes.
- Important! Any virtual hard disk that does not have a minimum IOPS value defined will default to 0. This means that VHD could end up resource-starved in some extreme cases.
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