The Resource Hosting Subsystem (Rhs.exe)...

Today I added my fourth node to my Windows Server 2008 R2 Cluster.

The cluster validation reported none errors, and I was about to Live Migrate one VM over to this new node.

It resulted in the following error:

The cluster resource host subsystem (RHS) stopped unexpectedly. An attempt will be made to restart it. This is usually due to a problem in a resource DLL. Please determine which resource DLL is causing the issue and report the problem to the resource vendor.

Strange, I thought, since my host was identical as the others, with every patch and updates installed.

I came across this Hotfix from MSFT: http://support.microsoft.com/kb/978527

Additional info about the RHS.exe can be found here: http://blogs.msdn.com/b/clustering/archive/2009/06/27/9806160.aspx

But in my case, there was an error related to NOD Eset Anti-Virus software.

After running Procmon, I found some registry keys that referred to Eset that caused the operation to fail.

After manually removing those entries, my Live Migration started to behave.

In general I must say, that I usually don’t install Anti-Virus on my Hyper-V hosts, since there is so much instability related to Hyper-V and especially when it comes  to Failover Clustering and Live Migration. But this server was recently used as a stand-alone Hyper-V host, and the uninstall procedure of NOD Eset did not remove everything as it should.

Moral: Be careful if you consider Anti-Virus on your Hyper-V hosts.

You will have some interesting problems with Hyper-V if you are using Anti-Virus on your host and do not configure it to exclude certain files and folders related to Hyper-V

Remember to exclude the following in your Anti-Virus software:

      *    VMMS.exe

·         MMS.exe

·         VMWP.exe

·         VMSWP.exe

Also exclude the root directory that contain your virtual machines and configuration files, and the following file extensions:

·         VHD

·         AVHD

·         VSV

·         ISO

·         VFD

·         XML