Taylor Browne has very recently created a new Wiki for the latest Hyper-V service packs, updates, and hotfixes for Windows Server 2012 R2 Hyper-V: http://social.technet.microsoft.com/wiki/contents/articles/20885.hyper-v-update-list-for-windows-server-2012-r2.aspx
Currently only one KB article KB2883200 is on the list but it will not take long before this list will grow. KB2773200 was the General Availability Rollup which was delivered at Windows Server 2012 R2 GA release in October 2013. This KB article also recommends to install KB2884846 which is the Windows Server 2012 R2 update rollup for October 2013 and includes “performance and reliability improvements”.
Many of the monthly update rollups for Windows Server 2012 R2 which come via Windows Update hide the exact details of what exactly has been changed or solved. It is very difficult to determine if it is specific to Hyper-V, clustering, networking, storage or all of them.
The November 2013 update rollup KB2887595 contains a fix for Hyper-V guest OS does not shut down when you restart the host computer that is running Windows Server 2012 R2 or Windows 8.1 which I encountered quite a lot in our environment. What seriously worries me however is that this same November 2013 update rollup also fixes things that are not mentioned in the list. For instance during a support case with Microsoft which dealt with VMs losing network connections on Windows Server 2012 R2 Hyper-V hosts, we learnt that a particular update part of the November rollup was also supposed to fix a problem with LBFO teaming. It turned out that it didn’t fix the problem for everyone as we still have to disable VMQ to keep our VM networking operational.
The December 2013 update rollup KB2903939 is more explicit on what updates have been made but I have a hard time figuring out what critical updates are made for enterprise servers. I have to filter through things like issues with client computers, Lumia 2520 camera app crashes, errors in Windows Live Messenger, mouse pointer stutters, input devices that fail and something that never enters a DRIPS, whatever that may be!
Here is another update that is not yet on the list and applies to Windows Server 2012 R2 and Hyper-V: Known issues after you enable data deduplication on CSV.
My advice to Microsoft:
be much more specific about what has been fixed
avoid stealth fixes (as we call them among Hyper-V MVP’s) which solve problems but are not described at all
separate the server updates from client and mobile.
be open and honest if updates turn out to be bad or broken (as we have seen several times in the past)
formalize the wiki by offering a hotfix/update list authorized by the product teams like the cluster team does with: http://support.microsoft.com/default.aspx?id=2784261: Recommended hotfixes and updates for Windows Server 2012-based Failover clusters.
This last support page is a very good initiative but it can take a while before updates are posted. A vital hotfix KB2908415 was announced only yesterday: Clustered shared volumes go offline or the Cluster service stops during VM backup on a Windows Server 2012 Hyper-V host server but is not yet on either the Cluster Update Wiki or the Official list for Windows Server 2012.
In other words: work to be done!