Accessing VM Discs on CEPH Filesystems

MrPaul

Active Member
Apr 27, 2019
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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.
 
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'
 
Try adding the disk extension .raw to that command.

Code:
qemu-img convert -f raw rdb:ceph/vm-116-disk-1.raw -O vmdk vm-116-disk-1.vmdk
 
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".
 
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.
 
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.
 
Yeah, I would imagine if ceph is not installed on that node it wouldn't have access to the rdb protocol.
 

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