libvirt migration failed : unknown protocol 'rbd'

Question

I've been using KVM/Qemu/libvirt/DRBD/Ceph for years but I've just had a strange issue when migrating a VM that has a Ceph RBD volume attached.

I've run this command to migrate the VM :

# virsh migrate --live --unsafe --verbose myvm qemu+ssh://IP/system tcp://IP

And I got this error :

Failed to open module: /usr/lib/x86_64-linux-gnu/qemu/block-rbd.so: failed to map segment from shared object
2024年12月04日T20:18:11.464782Z qemu-system-x86_64: -drive file=rbd:rbd/myvm_volume:id=libvirt:auth_supported=cephx\;none:mon_host=ceph01\:6789\;ceph02\:6789\;ceph03\:6789,file.password-secret=virtio-disk2-secret0,format=raw,if=none,id=drive-virtio-disk2: Unknown protocol 'rbd'

It's also visible in "/var/log/libvirt/qemu/myvm.log" on the destination host.

Looking for parts or the entire error on Google/DuckDuckGo gave me nothing.

Any idea why this is happening?

• eblock: It's been years since I had to deal with this message last time, back then it was a qemu version issue. Are your hypervisors identical? What OS are they running on? Which Ceph version? I would probably start by looking at qemu versions (and possible mismatches).
• jlecour: Both hypervisors are running Debian (same version) hence the same Qemu version. They have a minor difference in kernel version. I'll try to align them and try again.