Unable to mount disk (unsupported disk type) - specific VMs

[lurulak]

We are trying to make a file level restore from specific VMs (Windows) but we get the error "unable to mount disk: unsupported disk type". We only get this error with specific VMs we are using for Citrix (Citrix Master, not provisioned).

Last year when we used to restore the same (full) VMs, they worked fine.

No hardware changes were applied.

For testing prupose we did also a full VM restore to a test environment. The status for the job was "Success" but a step before "Restore completed successfully" says "Restoring Hard disk 1 (100GB) : 0 B restored at 0 KB/s [nbd]"

On target environment the is "created" but only with small or empty files:
.nvram (264.46KB)
.vmdk (0KB)
.vmsd (0.04KB)
.vmx (2.94KB)

Restore jobs (Full VM, File Level Restore) of other VMs are working fine.

We have opened a case for this (#05476624), but you maybe could help me with this one, too.

[HannesK]

Hello,
and welcome to the forums.

I guess it's something unsupported... could we get more information about what "Citrix" product / machine type this is about? I guess Xendesktop? What does "not provisioned" mean?

In the end, I guess support will find something in the logs that explains it.

Best regards,
Hannes

[lurulak]

Hello,

We are using Citrix Virtual Apps and Desktops (1912 LTSR CU3). With this we can use "Citrix Machine Creation Service" to provision multiple (terminal) servers based from a (master) VM in vCenter.

The master VMs OS are Windows Server 2019 or 2012R2. They are normal VMs on vCenter with Software (Office, Applications used for departments, etc.) and a Citrix agent installed.

I hope so, that support will find something in the logs

[HannesK]

Hello,

They are normal VMs on vCenter with Software

then it should work and support needs to check I was thinking about "special" VMs (linked clones etc.) that are common with virtual desktop infrastructures (VDI)

Best regards,
Hannes

[lurulak]

Hello Hannes

Thanks for your answers!

The provisioned VMs are kind a like linked clones, but the backed up VMs we want to restore from aren't "linked clones" or provisioned VMs. Provisioned VMs are not backed up because we are creating them from our base (master) VM, which are backed up but could not be restored.

Maybe it's a misconfiguraiton in hardware settings but AFAIK they were not changed. Could it be possible that a software configuration or software component within the VM (Citrix Agent) could prevent veeam from restoring?

Best regards

[lurulak]

Short update. This did not solve my problem yet but maybe it is helping someone else with a similar problem.

Veeam support presumed, that something with "Changed Block Tracking" (CBT) is not correct. In my case, CBT was already enabled in our backup jub. Even after CBT Reset (https://www.veeam.com/kb1113) and after a new Active Full Backup we're not able to restore guest files. Still same "unsupported disk type" error.

[greg.baird]

My first thought was "is the drive encrypted" and after a quick search found this referring to KB1459 - vmware-vsphere-f24/unable-to-mount-seco ... 58102.html

The other thought was if you had REFS volume in a 2019 VM but trying to restore on 2012 Server running VEEAM?

[HannesK]

Hello,
and welcome to the forums.

Yes, the guesses make sense to me for file level restore (his first scenario). For disk / VM restore (his second scenario), the filesystem is irrelevant and it also fails. So there needs to be something else.

I just checked the case and they are still investigating. I suggest to wait for the final result.

Best regards,
Hannes

[lurulak]

Short update:

The problem is CBT related. After the first time I did the CBT reset on the backup job I made a snapshot after (before next active full backup). Therefore the backup/restore still not worked. After I just did again a CBT reset (without creating any snapshots), backup/restore was successful until next active full backup.

As mentioned in https://kb.vmware.com/s/article/2139574 and in "Edit Backup Job -> Storage -> Advanced -> Tab: vSphere -> Changed block tracking" the VM must have no existing snapshots(!) for CBT to be enabled.

But we have to use snapshots on our Citrix master VMs due the possibility to rollback if there are any errors (with Microsoft updates or somethint).

We disabled all changed block tracking settings and also active full backup. The backup and restore of the VMs works now fine.