qcow2 corruption after snapshot or heavy disk I/O

w3ph

Member
Aug 20, 2011
29
0
21
So, this bug only happens when using the "obsolete" and "unsuggested" mode, right ?

That's what I've found - this only impacts virtio, not virtio-scsi. I obviously need to read the forums (or the docs) more often - I didn't realize that virtio's time had passed.
 

w3ph

Member
Aug 20, 2011
29
0
21
There are several benefits from using virtio-scsi instead of virtio:
  • virtio development has stopped and all efforts are used on virtio-scsi
  • performance is more or less on par - max 1-2% better with virtio
  • virtio-scsi passes unmap (trim, discard) through to the disk controller thereby regaining space
  • virtio-scsi is default for disks in proxmox 4
  • virtio vs virtio-scsi is more or less like comparing SATA with SAS. virtio-scsi is an intelligent controller

Thanks - excellent info. I'll go back and switch the virtio VMs to scsi next time each needs a reboot. A few percent difference in performance won't be noticeable in my environment and the advantages of scsi are clear.
 

tafkaz

Active Member
Dec 1, 2010
145
4
38
Geilenkirchen Germany
Hi,
quick question:
After p2v migration of a win2012 server i wanted to use scsi for the disks as well, but the VM will only boot in with the VD added as IDE0.
Additional SCSI VDs are not even shown in window's device manager.
What would be the correct driver to add for scsi support, and where do i get it.
thanks in advance
Sascha
 

tafkaz

Active Member
Dec 1, 2010
145
4
38
Geilenkirchen Germany
hm, i know that page, but that's still all about virtio drivers. from what i have understood, virtio is not being worked on anymore, so i thought that the complete driver set from fedorapeople would not be the way to go anymore.
Did i get that wrong?

thanks
Sascha
 

David Wilson

Member
Dec 26, 2017
8
0
6
42
Good day guys,

Season's greetings to you.

I can confirm that we experienced the same scary problem after running a snapshot on a VM with qcow2 disk images stored on NFS, presented to the VM as "Virtio SCSI". Others experiencing a similar problem seem to report the problem only occurring when using "Virtio Block" whereas we experienced the problem using "VirtIO SCSI".

I have also posted the same comment at https://forum.proxmox.com/threads/corrupt-filesystem-after-snapshot.32232/ which may be a similar discussion thread?
 
Dec 14, 2017
9
0
6
40
Good day guys,

Season's greetings to you.

I can confirm that we experienced the same scary problem after running a snapshot on a VM with qcow2 disk images stored on NFS, presented to the VM as "Virtio SCSI". Others experiencing a similar problem seem to report the problem only occurring when using "Virtio Block" whereas we experienced the problem using "VirtIO SCSI".

I have also posted the same comment at https://forum.proxmox.com/threads/corrupt-filesystem-after-snapshot.32232/ which may be a similar discussion thread?

Would it be safer to convert them to raw for now until this is resolved?
 

fabian

Proxmox Staff Member
Staff member
Jan 7, 2016
6,226
1,062
164
This is still a problem!

which we are unable to reproduce so far. please provide as much details as possible (versions, configs, logs, specifics about your setup, involved NFS server software and config, environment factors like load or outages, ...).
 

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