Consider the following scenario:
You have a Hyper-V virtual machine host computer that is running Windows 8.1, Windows RT 8.1, or Windows Server 2012 R2.
The virtual machines that are running on the computer use Solid State Drive (SSD) disks that handle TRIMs incorrectly.
In this scenario, virtual machines that are running on the computer perform slowly or crash.
To resolve this issue, install update rollup 2975719. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
2975719 August 2014 update rollup for Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates