Migrate from one ceph cluster to another

Community Support Storage
2

Considering the scarcity of attention to my post CONF 2017 / Storage Management: biggest pain to report in daily use of ONE, I would derive that not much has been changed in this field since then.

Hoping to be proven wrong though, with pointers to new features. :grinning:

So if I was to go manually and reduce downtime for live image migrations, one solution I would think of would be:

  1. Sync live images (e.g. using rsync), accepting temporarily that they may not be consistent
  2. Stop the VM
  3. Sync again (hopefully rsync will find a very limited number of blocks to sync this time)
  4. Detach old image, attach new image
  5. Start the VM

However, depending on your setup, you may have other solutions.

For example, if you use LVM, you may:

  1. create a new empty image on the new ceph DS
  2. attach it to the VM, as a new LVM PV, and live migrate all blocks from old PV to new PV.
  3. delete the old PV when empty, and detach the related image

You might have to consider separately things like /boot that may not be part of LVM. But the big part of the data can be migrated live.