Troubleshoot an issue where Ceph reports a HEALTH_WARN of 1 large omap objects. Adjust the omap object key threshold or number of placement groups (PG) to resolve this issue.
Ceph health is reporting a HEALTH_WARN for large Object Map (omap) objects.
ncn-m001# ceph -s
cluster:
id: 464f8ee0-667d-49ac-a82b-43ba8d377f81
health: HEALTH_WARN
1 large omap objects
clock skew detected on mon.ncn-m002, mon.ncn-m003
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: 11 pools, 600 pgs
objects: 1.82M objects, 2.6 TiB
usage: 6.1 TiB used, 57 TiB / 63 TiB avail
pgs: 600 active+clean
io:
client: 162 KiB/s rd, 9.0 MiB/s wr, 2 op/s rd, 890 op/s wr
Adjust the number of omap objects.
Use one of the options below to resolve the issue:
Use the ceph config command.
In the example below, the omap object key threshold is set to 350000, but it can be set to a higher number if desired.
ncn-m001# ceph config set client.osd osd_deep_scrub_large_omap_object_key_threshold 350000
In the example below, the rgw_usage_max_user_shards is set to 16 from 1. This can be set to a maximum of 32.
ceph config set client.radosgw rgw_usage_max_user_shards 16
Increase the number of PGs for the Ceph pool.
Get the current threshold and PG numbers.
ncn-m001# ceph osd pool autoscale-status
POOL SIZE TARGET SIZE RATE RAW CAPACITY RATIO TARGET RATIO BIAS PG_NUM NEW PG_NUM AUTOSCALE
cephfs_data 477.8M 3.0 64368G 0.0000 1.0 4 on
cephfs_metadata 781.9M 3.0 64368G 0.0000 4.0 16 on
.rgw.root 384.0k 3.0 64368G 0.0000 1.0 4 on
default.rgw.buckets.data 4509G 3.0 64368G 0.2102 0.2000 1.0 128 on
default.rgw.control 0 3.0 64368G 0.0000 1.0 4 on
default.rgw.buckets.index 1199M 3.0 64368G 0.0001 0.1800 1.0 128 on
default.rgw.meta 4898k 3.0 64368G 0.0000 1.0 4 on
default.rgw.log 0 3.0 64368G 0.0000 1.0 4 on
kube 307.0G 3.0 64368G 0.0143 0.1000 1.0 48 on
smf 1414G 2.0 64368G 0.0440 0.3000 1.0 256 on
default.rgw.buckets.non-ec 0 3.0 64368G 0.0000 1.0 4 on
Adjust the target_size_ratio value to increase the PGs for the pool.
This number should be increased a tenth or smaller at a time. Check the autoscale-status between each adjustment. When there is a change to the New PG NUM, stop adjusting the number.
In the example below, the target_size_ratio is set to 0.2.
ncn-m001# ceph osd pool set POOL_NAME target_size_ratio 0.2
Check to see if the change is taking effect.
ncn-m001# ceph osd pool autoscale-status
Watch the status of the Ceph health.
Verify the recovery traffic is taking place on the keys. The -w option can be used to watch the cluster.
ncn-m001# ceph -s