After backup my VM is frozen

Unimatrix001

New Member
May 19, 2025
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Hello there, my first post here.

I have a Windows Server 2016 VM which runs my SQL server and everything runs fine until backup. I have a backup plan which backs up my VM once a week (over the weekend) and after that my VM becomes unresponsive.

When I go to the Summary section of my VM where the IP address should be it says "guest agent not running" and there is no IP address. Through the Console I only see Login screen but it is not responsive. Remote desktop also doesn't work. The only thing that works is hard reset after which everything works fine until next backup.

Besides this VM I have few more (Linux and Windows) VM's which back up normally.

Proxmox VE version is 8.4.1.

I am novice to whole Proxmox and Linux environment so have patience :)

Kind regards,
Vedran
 
Hmm looks goot to me. 2 things: You have NUMA enabled? So it's a multi-socket CPU system? Did you try the backup without any redirecting USB device?

EDIT: How do you run your backup? Integrated backup option? PBS? Third party software?
 
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Hmm looks goot to me. 2 things: You have NUMA enabled? So it's a multi-socket CPU system? Did you try the backup without any redirecting USB device?

EDIT: How do you run your backup? Integrated backup option? PBS? Third party software?
Yes, it's a Lenovo two socket CPU system. That USB device is used for daily SQL database backups from within VM.

I use Proxmox integrated backup option.
 
Yes, it's a Lenovo two socket CPU system. That USB device is used for daily SQL database backups from within VM.

I use Proxmox integrated backup option.
Do you have the possibility of performing the backup while the USB hard disk is NOT being passed through to the VM?
 
What backup mode do you use? Have you tried Stop instead? Have you tried enabling Fleecing?

EDIT: I'm not sure if I have to say this explicitly: can you please try and see what happens when you use Stop and also when you enable Fleecing.
 
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If backup destination is too slow,
I/O is delayed up to timeout, then VM crash.
Be careful to not overlap within guest backup and pve backup.
By the way, PVE do VSS snapshot which, by default, break existing SQL chained backups (diff backup), this topic explain VSS options.
There is no problem if within guest SQL backups are only full.
 
If backup destination is too slow,
I/O is delayed up to timeout, then VM crash.
Be careful to not overlap within guest backup and pve backup.
By the way, PVE do VSS snapshot which, by default, break existing SQL chained backups (diff backup), this topic explain VSS options.
There is no problem if within guest SQL backups are only full.
It only happens at the end of backup and I get email notification that backup is successful. I do have backup within another guest that overlaps with PVE backup, do you think this is can be the problem or only if backup is within guest and the same VM is being backed up? I do hope you understand my question.

My SQL backups are full type.