Error in qcow2 snapshot for Backups

E

Eric Renfro

Guest
Hi, I'm getting an issue trying to run snapshot backups with qcow2 disks. The qcow2 storage itself is on an NFS server and the backup storage is to another NFS server, but the problem seems to be in "unable to detect lvm volume group", preventing it from doing one thing qcow2 was designed to be able to do, make live snapshots of it for backup purposes.

Shown below is the log of the issue:

INFO: starting new backup job: vzdump 121 --mode snapshot --compress 1 --storage nas3 --node ygg3
INFO: Starting Backup of VM 121 (qemu)
INFO: status = running
INFO: mode failure - unable to detect lvm volume group
INFO: trying 'suspend' mode instead
INFO: backup mode: suspend
INFO: ionice priority: 7
INFO: suspend vm
INFO: creating archive '/mnt/pve/nas3/dump/vzdump-qemu-121-2012_01_09-02_04_25.tgz'
INFO: adding '/mnt/pve/nas3/dump/vzdump-qemu-121-2012_01_09-02_04_25.tmp/qemu-server.conf' to archive ('qemu-server.conf')
INFO: adding '/mnt/pve/vmdisk/images/121/vm-121-disk-1.qcow2' to archive ('vm-disk-virtio0.qcow2')
INFO: Total bytes written: 811501056 (11.71 MiB/s)
INFO: archive file size: 288MB
INFO: resume vm
INFO: vm is online again after 102 seconds
INFO: Finished Backup of VM 121 (00:01:43)
INFO: Backup job finished successfully
TASK OK

Psi-Jack

 
if you store your virtual disks on NFS you cannot do live backups with vzdump.
 
tom said:
if you store your virtual disks on NFS you cannot do live backups with vzdump.
Click to expand...

Well, that's not the reason why. NFS is just the medium of the storage access layer, providing a shared access method to the disk images. What it seems to be is that vzdump isn't designed to work with qcow2's native snapshotting..

qemu-img snapshot -c backup disk.qcow2

Creates a snapshot, then you can use:

qemu-convert -c -O qcow2 -s backup disk.qcow2 backup.qcow2

To export that snapshot to disk, and finally:

qemu-img snapshot -d backup disk.qcow2

To delete that snapshot from the image again.

This should be something that is designed into vzdump which would streamline the backup process and not fallback to suspending the guest which interupts everything in the process.

Psi-Jack
 
again, vzdump does not use qcow2 snapshots, it uses LVM snapshots.
 
tom said:
again, vzdump does not use qcow2 snapshots, it uses LVM snapshots.
Click to expand...

It does appear that it would be possible to make a snapshot backup over nfs if the vm uses qcow2.
Such a feature would be a very useful enhancement to Proxmox.

Would you consider making such an enhancement when time allows or if it was funded?
Would you accept patches that add this feature?
 
e100 said:
Would you consider making such an enhancement when time allows or if it was funded?
Would you accept patches that add this feature?
Click to expand...

No, because that would only work for qcow2.

Instead we want to use the new live-backup features of qemu-kvm.
 
dietmar said:
No, because that would only work for qcow2.

Instead we want to use the new live-backup features of qemu-kvm.
Click to expand...

Was curious about this same thing myself. Picked the qcow2 format over the raw format so that I wouldn't have to thick provision my drives.

Is this "live-backup" feature still in the works?
 
Greetings!

Can the new live snapshot support (qcow2) available in the 2.2 version be used for live backups on non LVM storage, like ext3/4 partitions or NFS mounts?

Thanks!
 
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