2. If a down host comes up again and it's osd are started. Is data
still being copied, or does ceph see that checksums(?)
PG or RADOS object epoch I think. So if data hasn’t changed, the
recovery completes without having anything to do.
> are the same and just sets a pointer(?)
back to the old location?
Yes I mean the osdmap having the old osd on the node that was down.
Hmmm, I currently have pg's in 'active+remapped+backfill_wait' of a pool
rbd.backup. Of which I know nothing in it has changed. And those osd's listed[1] are
already up. Especially when you are getting at the 'end' of recovery where
osd_max_backfills=X has less effect and recovery takes longer. It would be nice to have
the "no work needed pg's" be processed quickly.
[1]
[18,25,41]p18 [18,41,17]
[5,0,25]p5 [5,0,4