On 11/8/18 11:26 AM, Sage Weil wrote: > On Thu, 8 Nov 2018, Mohamad Gebai wrote: >> 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. > Is newpool not a brand-new pool? It shouldn't have any snapshot state.. > although, yes, if it is empty and you don't care, then enabling that > option is okay (basically the pool-level snapshot metadata for the base > pool gets mirrored into the tier pool). Thanks, Sage. Yes newpool is empty, but testpool isn't. The command complains about adding testpool as a tier. Since we're talking about the base pool's metadata (empty) mirrored to the tier pool (not empty), is it safe to enable that option in that case? >> 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? > 'foward' is unsafe--do not use it. 'proxy' is what you want. Noted, thanks. Mohamad > > sage
