Ciao Burkhard, Burkhard Linke via ceph-users <ceph-users@ceph.io> writes:

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.

Similar here, just using opennebula.

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.

Similar, plus with opennebula it's embedded in the libvirt XML and not so easy to modify.

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.

Got it.

The rather old nautilus clusters might be problem, so if you want to try rbd live migration you need to test this first.

Will take that into consideration. The rbd mirror might actually also work for us, because a short downtime can likely be tolerated.

Not sure whether the script still exists, but I can try to dig it out if necessary.

If you still have it, would certainly be interested to take a glimpse at it, at least for inspiration. Sunny greetings from Switzerland, Nico -- Sustainable and modern Infrastructures by ungleich.ch