Hello, Ceph users, on my new cluster which I filled with testing data two weeks ago there are many repmapped PGs in backfill_wait state, probably as result of autoscaling the number of PGs per pool. But the recovery speed is quite low, in order of small MB/s and < 10 obj/s according to ceph -s. The cluster is otherwise idle, no client traffic after initial import, so I wonder why the backfill does not progress faster. Also, it seems like more pgs are getting remapped as existing ones get successfully backfilled - the percentage of misplaced objects is steadily around 6 % for the last two weeks. The PGs waiting for backfill all belong to the biggest pool I have according to "ceph pg dump | grep backfill", no surprise here. The pool has 229 TB of data and currently 128 PGs. It is replicated with k=4 m=2. The second biggest pool has only 23 TB of data: rados df POOL_NAME USED OBJECTS CLONES COPIES MISSING_ON_PRIMARY UNFOUND DEGRADED RD_OPS RD WR_OPS WR USED COMPR UNDER COMPR pool_with_backfill 229 TiB 10086940 0 60521640 0 0 0 0 0 B 72545009 54 TiB 0 B 0 B second_biggest_pool 23 TiB 1153174 0 6919044 0 0 0 0 0 B 38506397 16 TiB 0 B 0 B [...] I tried to do "ceph osd pool force-backfill $pool", it helped to speed things up a bit, but it still runs at 50-200 MB/s and 4-20 obj/s. The initial data import ran at around 600 MB/s. Is it normal or can I speed the recovery up a bit somehow? Output of ceph -s: cluster: id: ... health: HEALTH_WARN 2 large omap objects services: mon: 3 daemons, quorum istor11,istor21,istor31 (age 13d) mgr: istor31(active, since 3w), standbys: istor21, istor11 osd: 36 osds: 36 up (since 2w), 36 in (since 3w); 14 remapped pgs data: pools: 45 pools, 1505 pgs objects: 13.39M objects, 198 TiB usage: 303 TiB used, 421 TiB / 724 TiB avail pgs: 5335074/80345832 objects misplaced (6.640%) 1449 active+clean 34 active+clean+scrubbing 11 active+remapped+backfill_wait+forced_backfill 8 active+clean+scrubbing+deep 2 active+remapped+forced_backfill 1 active+remapped+backfilling+forced_backfill io: recovery: 69 MiB/s, 4 objects/s The OSDs are HDD-based with metadata on NVMe, 4 OSDs per node, and all the nodes have load average somewhere between 0.3 and 0.6. Thanks! -Yenya -- | Jan "Yenya" Kasprzak <kas at {fi.muni.cz - work | yenya.net - private}> | | https://www.fi.muni.cz/~kas/ GPG: 4096R/A45477D5 | We all agree on the necessity of compromise. We just can't agree on when it's necessary to compromise. --Larry Wall