Hi, we used the rbd live migration in the past to split up a cluster. The processed pools were used for image and volumes in our openstack cloud. Live migration mostly works, but if the RBD image is in use, you have to add some extra effort. Cinder for examples stores the mon information in its database, and this has to be updated. I used a script to migrate a RBD image, pause the instance, adjust the database entries, and live migrate the instance itself to another host to update the qemu/libvirt information. If the image is not actively used migration is trivial; if the image is attached to a stopped virtual machine migration is also trivial, but database entries have to be updated. The rather old nautilus clusters might be problem, so if you want to try rbd live migration you need to test this first. Not sure whether the script still exists, but I can try to dig it out if necessary. Best regards, Burkhard Linke On 3/19/26 13:28, Nico Schottelius via ceph-users wrote:

Hello,

I was wondering if there is any (recent, in general) method to merge to clusters. We have several older nautilus based clusters that are natively deployed. We also have several newer rook/kubernetes/squid based clusters.

In each data center we have both, alongside each other. While the clusters are running in separate networks, we could open the firewalls between them for a merge/migration.

My question is, is there any reasonable way of merging an old nautilus cluster into another existing squid cluster?

In theory, what would be amazing is something like a fluid process in which the newer cluster could retrieve items from the older cluster and once it has them, decommission them from the old cluster.

The live migration on https://docs.ceph.com/en/latest/rbd/rbd-live-migration/ seems to go a bit into the direction, but I am not sure if that works in our case.

We are looking at migrating around 500 rbd images in total.

Any hints appreciated!

Best regards,

Nico

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