8.3 beta, crashed Windows11 VM when trying to snapshot with memory

[Danp]

Which version of the VM Tools are you running? I assume the VM has a VTPM, correct?

Does a standard snapshot work? What about a snapshot with memory for a non-Windows 11 VM?

[manilx]

@Danp Standard snapshot works. Also after rebooting the VM after the crash the snapshot with memory worked.
Tools are:

VM has a VTPM.

[Danp]

Interesting. Maybe @stormi will know more about the reason for the crash.

[manilx]

@Danp Actually this is not the 1st time this happened as I now remember... Can't recall on which VM though. I 9 out of 10 only do standard snapshots

[stormi]

Does it always crash, or just sometimes?

[manilx]

@stormi I don't do this frequently or regularly. Since I reported it crashed 1 out of 4 (tests).

[stormi]

We'll try to reproduce. If you can upload the tarball created by xen-bugtool -y somewhere private, we can try to have a look at it.

[manilx]

@stormi said in 8.3 beta, crashed Windows11 VM when trying to snapshot with memory:

xen-bugtool -y

I did run the command on the host it occurred. How do I get the file out?

[stormi]

With scp (or a windows equivalent such as WinSCP maybe? I seldom use Windows)

[manilx]

@stormi Worked with sftp. (On macos).

I'll submit link via PM

[stormi]

Actually, I'm not sure checkpoints are supported, or snapshots of a suspended VM which as a vTPM: https://docs.xenserver.com/en-us/xenserver/8/vms/windows.html#constraints

I had already noted we need to investigate what this actually means, but this might explain why it crashes sometimes.

[manilx]

@stormi "You cannot snapshot or checkpoint a suspended VM with a vTPM attached."
The VM was running.... And we need snapshots for delta backups.

So let me know what you find.

[stormi]

@manilx I agree about snapshots. I don't know how we can checkpoint a VM without suspending it (I think it shortly suspends it and them resumes it), so I have trouble understanding XenServer's statement.

[jpwg3]

I'm experiencing similar issues on 2 out of 8 of my window server 2022 VMs. All 8 VMs with very similar configurations and no vTPM or secure boot on them. The only thing I see in common between the two that fail and the others is all the servers were set with static RAM 8Gb and Dynamic Max 8Gb. Except these two they were set 16 static and 8 dynamic. When I changed them to 8static and 8dynamic it ran just fine.

This isn't a deal breaker for me, but figured it might give you some insight or direction to look.

Xen Orchestra self compile commit ef3ad

[stormi]

Using dynamic memory is known to be prone to causing occasional issues. Thanks for the feedback.

Oh, by the way, regarding vTPM and snapshots, we finally established that it's fully supported by XenServer 8 and that the documentation was just out of date.