Accessing VM Discs on CEPH Filesystems

[MrPaul]

How do I access discs on CEPH filesystems (not cephfs). Specifially, I need to move a couple VMs to VMware but when I try to run qemu-img on them to convert them it's saying unknown protocl ceph.

root@proxmox-compute-1:/mnt/pve/cephfs/tmp# qemu-img convert -f raw ceph:vm-116-disk-1 -O vmdk disk-1.vmdk
qemu-img: Could not open 'ceph:vm-116-disk-1': Unknown protocol 'ceph'

I've also tried this directly on one of my CEPH storage hosts but I get the exact same error.

 

[Mihai]

qemu-img convert -f raw rdb:poolname/vm-116-disk-1 etc

 

[MrPaul]

That doesn't seem to work either.

root@proxmox-compute-1:/mnt/pve/cephfs/tmp# qemu-img convert -f raw rdb:ceph/vm-116-disk-1 -O vmdk vm-116-disk-1.vmdk
qemu-img: Could not open 'rdb:ceph/vm-116-disk-1': Unknown protocol 'rdb'

 

[Mihai]

Try adding the disk extension .raw to that command.

qemu-img convert -f raw rdb:ceph/vm-116-disk-1.raw -O vmdk vm-116-disk-1.vmdk

 

[MrPaul]

I just did with the same result. Note the the error isn't about an invalid/missing file from qemu-img but an unknown protocol of "rdb".

 

[Mihai]

Yeah that's fair, but unfortunately you can't 100% trust error messages.

Are you running these commands from a Ceph host (where ceph is actually installed)?

Other than that, I'm out of ideas, so hopefully someone else can chime in.

 

[MrPaul]

I'm running it from one of my compute nodes who does have access to the ceph filesystem via rdb. For what it's worth I did find a workaround by creating a backup & then extracting it to provide me the raw files for qemu-img.

 

[Mihai]

Yeah, I would imagine if ceph is not installed on that node it wouldn't have access to the rdb protocol.