Performance issues after Proxmox 7 migration

Vladimir Bulgaru

Active Member
Jun 1, 2019
214
47
33
35
Moscow, Russia
Hello!

I was wondering if Proxmox 7 has some architectural changes that need to be stored on VM and CT volumes.
My situation is the following:
  1. I have VMs and CTs stored on a PCIe SSD and OS is stored on the disk raid
  2. I have reinstalled the OS entirely to Proxmox 7 and restored the conf files of VMs and CTs
  3. I have relaunched all the VMs and CTs
It so happens that i see a huge performance drop on a Windows 10 VM and can't quite put a finger on it.

I am curious if this approach does not work well when upgrading the OS and i should've opted for a backup restore. I know that restoring the backup is safer and recommended approach, but what i'm interested to hear is how is my approach wrong, in case it is wrong.

Best!
 

Stefan_R

Proxmox Staff Member
Staff member
Jun 4, 2019
1,253
257
88
Vienna
That's a valid approach, as long as your disk images stay intact. How is the performance drop noticeable? (I/O, memory, CPU, graphics performance, etc...)

If possible, please post a VM config (qm config <vmid>) and your storage config (/etc/pve/storage.cfg).
 

Vladimir Bulgaru

Active Member
Jun 1, 2019
214
47
33
35
Moscow, Russia
That's a valid approach, as long as your disk images stay intact. How is the performance drop noticeable? (I/O, memory, CPU, graphics performance, etc...)

If possible, please post a VM config (qm config <vmid>) and your storage config (/etc/pve/storage.cfg).
Hello, @Stefan_R

Thank you for taking your time to address this. I guess a more detailed description of the situation is important, especially since downgrading Proxmox helped address the issue.

The setup is the following - I am storing the VMs and CTs on a Fusion-Io PCIe SSD, added as a LVM-thin storage. In both Proxmox 6 and 7 the drivers seem to work perfectly fine. The experiment has been done on the same machine, so faulty hardware in case of Proxmox 7 is out of the picture.

Same Window 10 VM works great on Proxmox 6. On Proxmox 7 it was lagging nightmarishly. It was so bad that even opening the File Explorer could take up to 20-30 seconds.

Currently the 2 strongest hypotheses are:
  1. Faulty Fusion-Io driver for Debian 11. What makes me doubt it is that the drivers are open-sourced and found on GitHub. I assume if there was an issue, it would have been reported by now;
  2. Some weird scheduler issue that bottlenecks the tasks at the hypervisor level. What makes me think this is a more likely cause is the fact that other Windows 10 VMs with less load seem to perform normally. The issues arise when the usage increases.
Very weird issue. In order to debug it further, I will try creating the VMs on a ZFS RAID made of spinning disks and compare the performance there. If the issue persists, it's almost 100% a Proxmox issue. Otherwise - it is an issue caused by the drivers.
 
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