• Virtual disk storage repository is filling up unexpectedly 
• Duplicate Base Disk volumes will be present in storage repositories 

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The old duplicated base disks can be manually deleted from the Hypervisor storage repository once the current version in use is correctly identified.

Background:

• It is important to confirm that all VMs involved in the upgrade process have been successfully rebooted completing the process
• On Studio add the column "Pending Updates" 
• If the status of "Pending Update" is "Yes" then the VM requires an update
• The MCS process will only update the VM only when the VM is rebooted from the Studio
• MCS will only delete the older base disk once it recognizes the update process is complete and no VMs are pending a reboot

Note: By default Citrix Delivery Controller/Cloud Connectors would trigger automatic deletion of the unused/stale base disks by the task named DisusedImageCleanUp which runs every 8 hours. The below steps can be followed only when some unexpected changes are performed in the Hypervisor. Please consider taking a necessary backup before deleting the disks as deleting the incorrect base disk would lead to MCS catalog corruption.

Workaround:
The UUID of the Current version of the Base Disk can be confirmed using the following steps:

• On the DDC:
  1. Run Get -ProvVM or Get -ProvVM -VMName (VMName = the name of a specific VM from the impacted catalog)
  2. Look at the results for AssignedImage and BootedImage
  3. Record the UUID of the BootedImage
  4. This UUID is the current/up-to-date Base Disk required by all the VMs in the catalog, the rest can be deleted once cross-referenced on the Hypervisor

 

• On the Hypervisor locate the disk with the UUID (This will use XenServer as an example):
  1. On the left plane select "Objects"
  2. Go to "Virtual Disks"
  3. Select each duplicate disk and check its UUID
  4. Compare the UUID of the selected disk to the UUID found from Get -ProvVM -> BootedImage 
  5. Once you have found the UUID that matches the BootImage UUID you have identified the most up-to-date Base Disk on XenServer
  6. The other duplicated disks can be deleted and the space will be reclaimed 

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Problem Cause

During upgrade the MCS process creates a copy of the base disk to write the upgrades onto. Once it is satisfied that the process has been complete and the corresponding vms rebooted the old base disk will be deleted by the DisusedImageCleanUp portion of the MCS Process.
In certain scenarios the old base disk may not get deleted at the end of the MCS upgrade process and take up storage resources