Since we have installed our Microsoft Hyper-V Cluster on the Cisco UCS, Microsoft released some patches for Hyper-V, Windows and Clustering.
There are two really important Updates which I would recommend for Hyper-V Clusters.
The first is Service Pack 1 for Windows Server 2008 R2 and Hyper-V Server 2008 R2. Service Pack 1 brings a lot of Hotfixes for Hyper-V, Failover Cluster Feature and other Microsoft Server features. And it brings also a two new features called Dynamic Memory and RemoteFX.
The second one is a hotfix for Servers with Intel Westmere or Sandy Bridge and has a large amount of physical memory. Most of the Cisco UCS Blades will meet this configuration. You can get more information on this Hyper-V hotfix here.
This two updates will bring you a much better experience with your Hyper-V Cluster. It will improve performance, stability and it will add new features.
If you are using Microsoft Hyper-V with new Intel Sandy Bridge or Intel Westmere processors and our server has over 48GB of physical RAM you may get a performance decrease. Microsoft released a hotfix (KB2517329) for this problem.
This could also be a problem with a lot of Hyper-V installations on Cisco UCS, because the most of them will use more than 48GB of memory.
The performance decrease could show its self in the the following issues:
The CPU usage is high and the server responds slowly when you copy large files on the computer. For example, you copy a 10-GB file
The disk I/O performance of the virtual machines (VMs) is slow
Windows takes a long time to start
The hotfix is not include in Service Pack 1 for Hpyer-V R2 or Windows Server 2008 R2.
For more information about this you can check KB2517329