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Question

XenServer passthrough disk filter

  • February 2, 2026
  • 3 replies
  • 9 views
A
Novice
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Hi,

 

We got an error message on snapshot when we tried to backup a vm with a passthrough disk. We use xcp-ng as hypervisor (XenServer). We tried disk filter with the name and the path, we added the setting bEnableDiskFiltersForXen to true but nothing solve the problem

 

Last backup job [98] did not complete successfully for the VM group with error: Killed by admin. Reason:[]. Source: commserve01, Process: JobManager Unable to create a virtual machine snapshot of [test-backup01_rhel9]. [] Please check the virtual machine snapshot tree. Source: cv-proxy01, Process: vsbkpLast backup job [98] did not complete successfully for the VM group with error: Killed by admin. Reason:[]. Source: commserve01, Process: JobManager Unable to create a virtual machine snapshot of [test-backup01_rhel9]. [] Please check the virtual machine snapshot tree. Source: cv-proxy01, Process: vsbkp

 

We tried a backup with the same vm without the passtrough disk and it was successfull but removing the disk is not a viable option for a daily backup.

 

How can we backup with the passtrough disk with a filter that works?

3 replies

J
Vaulter
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  • Jace RossVaulter
  • Vaulter
  • February 2, 2026

Hi Alexandre,

Passthrough disks are typically not supported for snapshotting in many hypervisors because the device isn’t a virtual disk the hypervisor has control of.

When Commvault Cloud tries to backup your VM it will send a snapshot request for the VM (most, if not, all hypervisors will always attempt to snapshot all disks associated to the VM when a snapshot request is made). The result of the snapshot is what Commvault uses to proceed with the backup. In your example Xen is stating that the snapshot failed. With a failed snapshot Commvault cannot proceed with the backup.

If you create a snapshot in Xen without Commvault, does it succeed with the passthrough disk attached?
https://docs.xenserver.com/en-us/xenserver/8/dr/snapshots.html

If snapshots do not work in Xen, I would suggest file system protection of any VMs with disk passthrough.

Jace Ross, Senior Technical SME
A
Novice
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  • AlexandreNovice
  • Author
  • Novice
  • February 2, 2026

Hi Jace,

 

When we tried to snapshot the VM with the passthrough disk, it doesn’t work. If we put a tag [NOSNAP] on the passthrough disk and still attached to the VM, we are able to snapshot the VM. When we tried to do a backup with this tag, it does not work.

J
Vaulter
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  • Jace RossVaulter
  • Vaulter
  • February 2, 2026

Hi Alexandre,

I believe the issue may be that Commvault requests don’t leverage disk tags in Xen. I cannot be certain though. I would recommend raising a support incident to have our team investigate further and get confirmation if this behaviour is expected.
 

Jace Ross, Senior Technical SME
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