Use this procedure to examine the Ceph cluster and troubleshoot issues where Ceph runs out of space and the Kubernetes cluster cannot write data. The OSDs need to be reweighed to move data from the drive and get it back under the warning threshold.
When a single OSD for a pool fills up, the pool will go into read-only mode to protect the data. This can occur if the data distribution is unbalanced or if more storage nodes are needed.
Return the Ceph cluster to a healthy state after it reports a full OSD.
The commands in this procedure need to be run on a ceph-mon node.
View the status of the Ceph cluster.
ncn-m001# ceph -s
cluster:
id: 64e553c3-e7d9-4636-81a4-56f26c1b20e1
health: HEALTH_ERR
1 full osd(s)
13 pool(s) full
services:
mon: 3 daemons, quorum ncn-s001,ncn-s002,ncn-s003 (age 20h)
mgr: ncn-s003(active, since 9d), standbys: ncn-s001, ncn-s002
mds: cephfs:1 {0=ncn-s002=up:active} 2 up:standby
osd: 18 osds: 18 up (since 20h), 18 in (since 9d)
rgw: 3 daemons active (ncn-s001.rgw0, ncn-s002.rgw0, ncn-s003.rgw0)
data:
pools: 13 pools, 288 pgs
objects: 2.98M objects, 11 TiB
usage: 32 TiB used, 24 TiB / 56 TiB avail
pgs: 288 active+clean
io:
client: 379 KiB/s rd, 2.2 KiB/s wr, 13 op/s rd, 1 op/s wr
View the Ceph health detail.
The OSD_NEARFULL list can have multiple results. Take a note of the returned results to compare with the output of the ceph osd df output.
ncn-m001# ceph health detail
HEALTH_ERR 1 nearfull osd(s); 13 pool(s) nearfull; Degraded data redundancy (low space): 3 pgs backfill_toofull
OSD_NEARFULL 1 nearfull osd(s)
osd.9 is near full <<-- Note this value
View the storage utilization of the cluster and pools.
ncn-m001# ceph df
RAW STORAGE:
CLASS SIZE AVAIL USED RAW USED %RAW USED
ssd 56 TiB 24 TiB 32 TiB 32 TiB 57.15
TOTAL 56 TiB 24 TiB 32 TiB 32 TiB 57.15
POOLS:
POOL ID STORED OBJECTS USED %USED MAX AVAIL
cephfs_data 1 39 MiB 387 121 MiB 0.10 39 GiB
cephfs_metadata 2 257 MiB 123 770 MiB 0.64 39 GiB
.rgw.root 3 3.7 KiB 8 400 KiB 0 39 GiB
defaults.rgw.buckets.data 4 0 B 0 0 B 0 39 GiB
default.rgw.control 5 0 B 8 0 B 0 39 GiB
defaults.rgw.buckets.index 6 0 B 0 0 B 0 39 GiB
default.rgw.meta 7 22 KiB 114 4.4 MiB 0 39 GiB
default.rgw.log 8 0 B 207 0 B 0 39 GiB
kube 9 220 GiB 61.88k 661 GiB 84.93 39 GiB
smf 10 10 TiB 2.86M 31 TiB 99.63 39 GiB
default.rgw.buckets.index 11 5.9 MiB 14 5.9 MiB 0 39 GiB
default.rgw.buckets.data 12 145 GiB 48.11k 436 GiB 78.81 39 GiB
default.rgw.buckets.non-ec 13 305 KiB 34 1.9 MiB 0 39 GiB
View the utilization of the OSDs to see if data is not balanced across them.
In the example below, the OSD.9 value is showing that it is 95.17 percent full.
ncn-m001# ceph osd df
ID CLASS WEIGHT REWEIGHT SIZE RAW USE DATA OMAP META AVAIL %USE VAR PGS STATUS
1 ssd 3.49219 1.00000 3.5 TiB 2.1 TiB 2.1 TiB 6.3 MiB 3.9 GiB 1.4 TiB 60.81 1.06 57 up
4 ssd 3.49219 1.00000 3.5 TiB 2.0 TiB 2.0 TiB 133 KiB 3.7 GiB 1.5 TiB 57.58 1.01 56 up
5 ssd 3.49219 1.00000 3.5 TiB 2.1 TiB 2.1 TiB 195 KiB 3.5 GiB 1.4 TiB 61.33 1.07 49 up
6 ssd 3.49219 1.00000 3.5 TiB 1.2 TiB 1.2 TiB 321 KiB 2.4 GiB 2.3 TiB 33.90 0.59 40 up
7 ssd 3.49219 1.00000 3.5 TiB 1.5 TiB 1.5 TiB 1012 KiB 2.9 GiB 2.0 TiB 43.03 0.75 39 up
8 ssd 3.49219 1.00000 3.5 TiB 1.7 TiB 1.7 TiB 194 KiB 4.0 GiB 1.8 TiB 47.96 0.84 47 up
0 ssd 3.49219 1.00000 3.5 TiB 2.8 TiB 2.8 TiB 485 KiB 5.2 GiB 696 GiB 80.53 1.41 75 up
**9 ssd 3.49219 1.00000 3.5 TiB 3.3 TiB 3.3 TiB 642 KiB 6.1 GiB 173 GiB 95.17 1.67 67 up**
10 ssd 3.49219 1.00000 3.5 TiB 1.7 TiB 1.7 TiB 6.7 MiB 3.1 GiB 1.8 TiB 47.74 0.84 68 up
11 ssd 3.49219 1.00000 3.5 TiB 2.8 TiB 2.8 TiB 1.1 MiB 5.4 GiB 675 GiB 81.14 1.42 78 up
2 ssd 3.49219 1.00000 3.5 TiB 2.2 TiB 2.2 TiB 27 KiB 4.0 GiB 1.3 TiB 62.14 1.09 40 up
3 ssd 3.49219 1.00000 3.5 TiB 2.3 TiB 2.3 TiB 445 KiB 4.4 GiB 1.2 TiB 65.90 1.15 55 up
12 ssd 3.49219 1.00000 3.5 TiB 541 GiB 540 GiB 1006 KiB 1.3 GiB 3.0 TiB 15.14 0.27 48 up
13 ssd 3.49219 1.00000 3.5 TiB 2.6 TiB 2.6 TiB 176 KiB 4.9 GiB 895 GiB 74.96 1.31 56 up
14 ssd 3.49219 1.00000 3.5 TiB 1.8 TiB 1.8 TiB 6.4 MiB 3.3 GiB 1.7 TiB 52.03 0.91 48 up
15 ssd 3.49219 1.00000 3.5 TiB 1.2 TiB 1.2 TiB 179 KiB 2.5 GiB 2.3 TiB 34.44 0.60 41 up
Use the ceph osd reweight command on the OSD to move data from the drive and get it back under the warning threshold of 85 percent.
This command tells Ceph that the drive can now only hold 80 percent of the usable space (CRUSH weight).
ncn-m001# ceph osd reweight osd.9 0.80
Confirm the reweight command made the change.
In this example, the new reweight is .79999 and the use is now at 80 percent.
ncn-m001# ceph osd df
ID CLASS WEIGHT REWEIGHT SIZE RAW USE DATA OMAP META AVAIL %USE VAR PGS STATUS
1 ssd 3.49219 1.00000 3.5 TiB 2.1 TiB 2.1 TiB 7.1 MiB 4.7 GiB 1.4 TiB 60.91 1.07 57 up
4 ssd 3.49219 1.00000 3.5 TiB 2.0 TiB 2.0 TiB 137 KiB 3.7 GiB 1.5 TiB 57.65 1.01 56 up
5 ssd 3.49219 1.00000 3.5 TiB 2.1 TiB 2.1 TiB 207 KiB 4.0 GiB 1.3 TiB 61.42 1.07 49 up
6 ssd 3.49219 1.00000 3.5 TiB 1.2 TiB 1.2 TiB 293 KiB 2.4 GiB 2.3 TiB 33.94 0.59 40 up
7 ssd 3.49219 1.00000 3.5 TiB 1.5 TiB 1.5 TiB 1012 KiB 2.9 GiB 2.0 TiB 43.08 0.75 39 up
8 ssd 3.49219 1.00000 3.5 TiB 1.7 TiB 1.7 TiB 198 KiB 3.1 GiB 1.8 TiB 48.00 0.84 47 up
0 ssd 3.49219 1.00000 3.5 TiB 3.0 TiB 3.0 TiB 497 KiB 5.5 GiB 522 GiB 85.40 1.49 80 up
**9 ssd 3.49219 0.79999 3.5 TiB 2.8 TiB 2.8 TiB 650 KiB 6.1 GiB 687 GiB 80.80 1.41 51 up**
10 ssd 3.49219 1.00000 3.5 TiB 2.0 TiB 2.0 TiB 7.2 MiB 3.6 GiB 1.5 TiB 57.35 1.00 75 up
11 ssd 3.49219 1.00000 3.5 TiB 2.8 TiB 2.8 TiB 1.1 MiB 5.3 GiB 664 GiB 81.43 1.42 82 up
2 ssd 3.49219 1.00000 3.5 TiB 2.2 TiB 2.2 TiB 31 KiB 4.0 GiB 1.3 TiB 62.22 1.09 40 up
3 ssd 3.49219 1.00000 3.5 TiB 2.3 TiB 2.3 TiB 457 KiB 4.2 GiB 1.2 TiB 65.98 1.15 55 up
12 ssd 3.49219 1.00000 3.5 TiB 542 GiB 541 GiB 990 KiB 1.3 GiB 3.0 TiB 15.16 0.27 48 up
13 ssd 3.49219 1.00000 3.5 TiB 2.6 TiB 2.6 TiB 196 KiB 4.9 GiB 892 GiB 75.05 1.31 56 up
14 ssd 3.49219 1.00000 3.5 TiB 1.8 TiB 1.8 TiB 7.1 MiB 3.3 GiB 1.7 TiB 52.10 0.91 48 up
15 ssd 3.49219 1.00000 3.5 TiB 1.2 TiB 1.2 TiB 171 KiB 2.7 GiB 2.3 TiB 34.48 0.60 41 up
TOTAL 56 TiB 32 TiB 32 TiB 27 MiB 62 GiB 24 TiB 57.19
MIN/MAX VAR: 0.27/1.49 STDDEV: 18.51
Monitor the Ceph cluster during recovery.
ncn-m001# ceph -s