Copying Citrix PVS’d Vdisks while running can cause WMI to break

In consulting land we’ve noticed a few cases recently where a 24/7 shop decided to snapshot a running Citrix PVS’d VDisk so they could make updates with the minimal amount of downtime possible. This is becoming more and more common in healthcare situations where clients are unable to stand any amount of downtime for a change window, etc. On at least two separate occasions, we’ve noticed that doing this seems to break WMI on the image. This isn’t necessarily a Citrix problem, but more a problem that you might expect to get when copying a running image that may have active hooks into lots of data and running dll’s, etc.

The resolution in both cases we observed was to re-register WMI, and then re-register the Citrix namespace. For instructions on how to do that, see the below command line steps:

First, obviously switch the Vdisk from Standard mode to Private.

To re-register the WMI components, run the following commands at the command prompt:

cd /d %windir%\system32\wbem
for %i in (*.dll) do RegSvr32 -s %i
for %i in (*.exe) do %i /RegServer

Following these steps, it is then neccessary to re-register the Citrix namespace:

From the command line:

cd /d %ProgramFiles%\citrix\system32\citrix\wmi
for /f %s in (‘dir /b *.mof *.mfl’) do mofcomp %s

Once completed, you should be able to reseal your image and deploy it once again in Standard mode without issue.

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