I've been struggling with this one for a few days now. We had an OSD report as near full a few days ago. Had this happen a couple of times before and a reweight-by-utilization has sorted it out in the past. Tried the same again but this time we ended up with a couple of pgs in a state of backfill_toofull and a handful of misplaced objects as a result.
Tried doing the reweight a few more times and it's been moving data around. We did have another osd trigger the near full alert but running the reweight a couple more times seems to have moved some of that data around a bit better. However, the original near_full osd doesn't seem to have changed much and the backfill_toofull pgs are still there. I'd keep doing the reweight-by-utilization but I'm not sure if I'm heading down the right path and if it will eventually sort it out.
We have 14 pools, but the vast majority of data resides in just one of those pools (pool 20). The pgs in the backfill state are in pool 2 (as far as I can tell). That particular pool is used for some cephfs stuff and has a handful of large files in there (not sure if this is significant to the problem).
All up, our utilization is showing as 55.13% but some of our OSDs are showing as 76% in use with this one problem sitting at 85.02%. Right now, I'm just not sure what the proper corrective action is. The last couple of reweights I've run have been a bit more targetted in that I've set it to only function on two OSDs at a time. If I run a test-reweight targetting only one osd, it does say it will reweight OSD 9 (the one at 85.02%). I gather this will move data away from this OSD and potentially get it below the threshold. However, at one point in the past couple of days, it's shown as no OSDs in a near full state, yet the two pgs in backfill_toofull didn't change. So, that's why I'm not sure continually reweighting is going to solve this issue.
I'm a long way from knowledgable on Ceph so I'm not really sure what information is useful here. Here's a bit of info on what I'm seeing. Can provide anything else that might help.
Basically, we have a three node cluster but only two have OSDs. The third is there simply to enable a quorum to be established. The OSDs are evenly spread across these two needs and the configuration of each is identical. We are running Jewel and are not in a position to upgrade at this stage.
# ceph --version
ceph version 10.2.11 (e4b061b47f07f583c92a050d9e84b1813a35671e)
# ceph health detail
HEALTH_WARN 2 pgs backfill_toofull; 2 pgs stuck unclean; recovery 33/62099566 objects misplaced (0.000%); 1 near full osd(s)
pg 2.52 is stuck unclean for 201822.031280, current state active+remapped+backfill_toofull, last acting [17,3]
pg 2.18 is stuck unclean for 202114.617682, current state active+remapped+backfill_toofull, last acting [18,2]
pg 2.18 is active+remapped+backfill_toofull, acting [18,2]
pg 2.52 is active+remapped+backfill_toofull, acting [17,3]
recovery 33/62099566 objects misplaced (0.000%)
osd.9 is near full at 85%
# ceph osd df
ID WEIGHT REWEIGHT SIZE USE AVAIL %USE VAR PGS
2 1.37790 1.00000 1410G 842G 496G 59.75 1.08 33
3 1.37790 0.45013 1410G 1079G 259G 76.49 1.39 21
4 1.37790 0.95001 1410G 1086G 253G 76.98 1.40 44
5 1.37790 1.00000 1410G 617G 722G 43.74 0.79 43
6 1.37790 0.65009 1410G 616G 722G 43.69 0.79 39
7 1.37790 0.95001 1410G 495G 844G 35.10 0.64 40
8 1.37790 1.00000 1410G 732G 606G 51.93 0.94 52
9 1.37790 0.70007 1410G 1199G 139G 85.02 1.54 37
10 1.37790 1.00000 1410G 611G 727G 43.35 0.79 41
11 1.37790 0.75006 1410G 495G 843G 35.11 0.64 32
0 1.37790 1.00000 1410G 731G 608G 51.82 0.94 43
12 1.37790 1.00000 1410G 851G 487G 60.36 1.09 44
13 1.37790 1.00000 1410G 378G 960G 26.82 0.49 38
14 1.37790 1.00000 1410G 969G 370G 68.68 1.25 37
15 1.37790 1.00000 1410G 724G 614G 51.35 0.93 35
16 1.37790 1.00000 1410G 491G 847G 34.84 0.63 43
17 1.37790 1.00000 1410G 862G 476G 61.16 1.11 50
18 1.37790 0.80005 1410G 1083G 255G 76.78 1.39 26
19 1.37790 0.65009 1410G 963G 375G 68.29 1.24 23
20 1.37790 1.00000 1410G 724G 614G 51.38 0.93 42
TOTAL 28219G 15557G 11227G 55.13
MIN/MAX VAR: 0.49/1.54 STDDEV: 15.57
# ceph pg ls backfill_toofull
pg_stat objects mip degr misp unf bytes log disklog state state_stamp v reported up up_primary acting acting_primary last_scrub scrub_stamp last_deep_scrub deep_scrub_stamp
2.18 9 0 0 18 0 0 3653 3653 active+remapped+backfill_toofull 2020-10-29 05:31:20.429912 610'549153 656:390372 [9,12] 9 [18,2] 18 594'547482 2020-10-25 20:28:39.680744 594'543841 2020-10-21 21:21:33.092868
2.52 15 0 0 15 0 0 4883 4883 active+remapped+backfill_toofull 2020-10-29 05:31:28.277898 652'502085 656:367288 [17,9] 17 [17,3] 17 594'499108 2020-10-26 11:06:48.417825 594'499108 2020-10-26 11:06:48.417825
pool : 17 18 19 11 20 21 12 13 0 14 1 15 2 16 | SUM
--------------------------------------------------------------------------------------------------------------------------------
osd.4 3 0 0 0 9 2 0 0 12 1 9 0 7 1 | 44
osd.17 1 0 0 0 7 3 1 0 8 1 17 1 11 0 | 50
osd.18 0 0 0 0 9 0 0 0 4 0 7 0 5 0 | 25
osd.5 0 0 0 2 5 1 1 0 5 0 16 0 11 2 | 43
osd.6 0 1 0 1 5 2 0 0 9 0 13 1 7 0 | 39
osd.19 0 0 1 0 8 2 0 1 2 0 6 0 3 0 | 23
osd.7 0 0 0 0 4 1 1 0 3 0 12 0 19 0 | 40
osd.8 0 1 0 0 6 3 0 2 10 1 13 1 15 0 | 52
osd.9 1 0 2 0 10 2 0 0 4 1 6 1 10 0 | 37
osd.10 0 0 1 1 5 2 0 1 7 0 12 0 11 1 | 41
osd.20 1 0 0 0 6 1 0 1 7 0 8 1 17 0 | 42
osd.11 0 0 0 0 4 1 1 1 5 0 11 0 9 0 | 32
osd.12 0 0 1 1 7 1 0 0 5 1 12 1 14 1 | 44
osd.13 0 2 0 0 3 1 0 0 10 1 11 0 10 0 | 38
osd.0 0 1 0 1 6 3 0 1 7 0 11 0 13 0 | 43
osd.14 1 0 0 0 8 1 1 0 4 1 12 0 9 0 | 37
osd.15 1 0 2 1 6 1 1 0 8 0 7 0 6 2 | 35
osd.2 0 2 1 0 7 2 1 0 7 1 4 1 6 0 | 32
osd.3 0 0 0 0 9 0 0 0 2 0 4 0 5 0 | 20
osd.16 0 1 0 1 4 3 1 1 9 0 9 1 12 1 | 43
--------------------------------------------------------------------------------------------------------------------------------
SUM : 8 8 8 8 128 32 8 8 128 8 200 8 200 8 |
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