Hi all, I'm going over the pool migration using a cache tier process explained here [1]. There are a couple of issues with it: 1. if the pool has RBD images in it, it cannot be added as a tier: $> ceph osd tier add newpool testpool --force-nonempty Error ENOTEMPTY: tier pool 'testpool' has snapshot state; it cannot be added as a tier without breaking the pool This happens even though there are no snapshots in the pool, but it can be mitigated by enabling mon_debug_unsafe_allow_tier_with_nonempty_snaps. 2. the 'forward' mode seems to be causing some issues as seen in this issue [2] (writes reordering) and in the comment here [3]. Using the 'proxy' mode though seems to achieve the same ends for pool migration. Are there any thoughts on this procedure? Should the 'proxy' mode be used instead of the 'forward' mode? And how safe is it to enable tiering with snapshot state on a production cluster? Thanks, Mohamad [1] https://ceph.com/geen-categorie/ceph-pool-migration/ [2] http://tracker.ceph.com/issues/12814 [3] https://github.com/ceph/ceph/commit/d7da68848a8551390a82cd6c46ffef00f98e9e59
