Backup error on lxc image with rbd journaling enabled

[fxandrei]

So i have configured mirroring on some images in a proxmox cluster with ceph.
I have enable journaling on all images. But now i have a problem when backing a lxc container that has journaling enabled on its images.

I get this :

INFO: create storage snapshot 'vzdump'
RBD image feature set mismatch. You can disable features unsupported by the kernel with "rbd feature disable pool/vm-111-disk-0 journaling".
In some cases useful info is found in syslog - try "dmesg | tail".
rbd: sysfs write failed
umount: /mnt/vzsnap0/: not mounted.
command 'umount -l -d /mnt/vzsnap0/' failed: exit code 32
ERROR: Backup of VM 111 failed - can't map rbd volume vm-111-disk-0@vzdump: rbd: sysfs write failed

I have proxmox 6.4-13 and ceph 14.2.22

Has anyone encountered this ?

 

[fxandrei]

I havent been able to find any solution to this, but the biggest problem is not the backup, is the fact that the lxc containers dont start anymore if they have that feature enabled.

That means i cannot use mirroring with ceph.

Did anyone manage to do something about this ?

 

[fxandrei]

So i saw that the image cannot be mounted.
So i get the same error if i run something like this:
rbd map vm-102-disk-0 --pool storage_vms

But if i install rbd-nbd i dont get any errors.

Im not sure what to think of it.

 

[fxandrei]

1st about my last post.
its not enough to install rbd-nbd.
So after you install it you can use it to map the image to a device.
Something like this :
rbd-nbd map storage_vms/vm-102-disk-0

Now, from my understanting, it seems containers need krbd in order to work (if using ceph images).
The problem is that that feature is just not supported in the current version, as seen here: https://docs.ceph.com/en/latest/rbd/rbd-config-ref/

If you look for journaling you get this:

Description
Journaling support depends on exclusive lock support. Journaling records all modifications to an image in the order they occur. RBD mirroring can utilize the journal to replicate a crash-consistent image to a remote cluster. It is best to let rbd-mirror manage this feature only as needed, as enabling it long term may result in substantial additional OSD space consumption.

Internal value
64

CLI value
journaling

Added in
v10.0.1 (Jewel)

KRBD support
no

Default
no

So i guess there is no way to use mirroring on images used by containers (for now at least).

The only other alternative would be snapshots, but i havent been able to make that work.

 

[fxandrei]

I think this can be closed. There is no way to do this for now.