Good morning, Cephadm Reef 18.2.1. We recently added 4 hosts and changed a failure domain from host to datacenter which is the reason for the large misplaced percentage. We were seeing some pretty crazy spikes in "OSD Read Latencies" and "OSD Write Latencies" on the dashboard. Most of the time everything is well but then for periods of time, 1-4 hours, latencies will go to 10+ seconds for one or more OSDs. This also happens outside scrub hours and it is not the same OSDs every time. The OSDs affected are HDD with DB/WAL on NVMe. Log snippet: " ... 2024-03-22T06:48:22.859+0000 7fb184b52700 1 heartbeat_map is_healthy 'OSD::osd_op_tp thread 0x7fb169898700' had timed out after 15.000000954s 2024-03-22T06:48:22.859+0000 7fb185b54700 1 heartbeat_map is_healthy 'OSD::osd_op_tp thread 0x7fb169898700' had timed out after 15.000000954s 2024-03-22T06:48:22.864+0000 7fb169898700 1 heartbeat_map clear_timeout 'OSD::osd_op_tp thread 0x7fb169898700' had timed out after 15.000000954s 2024-03-22T06:48:22.864+0000 7fb169898700 0 bluestore(/var/lib/ceph/osd/ceph-112) log_latency slow operation observed for submit_transact, latency = 17.716707230s 2024-03-22T06:48:22.880+0000 7fb1748ae700 0 bluestore(/var/lib/ceph/osd/ceph-112) log_latency_fn slow operation observed for _txc_committed_kv, latency = 17.732601166s, txc = 0x55a5bcda0f00 2024-03-22T06:48:38.077+0000 7fb184b52700 1 heartbeat_map is_healthy 'OSD::osd_op_tp thread 0x7fb169898700' had timed out after 15.000000954s 2024-03-22T06:48:38.077+0000 7fb184b52700 1 heartbeat_map is_healthy 'OSD::osd_op_tp thread 0x7fb169898700' had timed out after 15.000000954s ... " " [root@dopey ~]# ceph -s cluster: id: 8ee2d228-ed21-4580-8bbf-0649f229e21d health: HEALTH_WARN 1 failed cephadm daemon(s) Low space hindering backfill (add storage if this doesn't resolve itself): 1 pg backfill_toofull services: mon: 5 daemons, quorum lazy,jolly,happy,dopey,sleepy (age 3d) mgr: jolly.tpgixt(active, since 10d), standbys: dopey.lxajvk, lazy.xuhetq mds: 1/1 daemons up, 2 standby osd: 540 osds: 539 up (since 6m), 539 in (since 15h); 6250 remapped pgs data: volumes: 1/1 healthy pools: 15 pools, 10849 pgs objects: 546.35M objects, 1.1 PiB usage: 1.9 PiB used, 2.3 PiB / 4.2 PiB avail pgs: 1425479651/3163081036 objects misplaced (45.066%) 6224 active+remapped+backfill_wait 4516 active+clean 67 active+clean+scrubbing 25 active+remapped+backfilling 16 active+clean+scrubbing+deep 1 active+remapped+backfill_wait+backfill_toofull io: client: 117 MiB/s rd, 68 MiB/s wr, 274 op/s rd, 183 op/s wr recovery: 438 MiB/s, 192 objects/s " Anyone know what the issue might be? Given that is happens on and off with large periods of time in between with normal low latencies I think it unlikely that it is just because the cluster is busy. Also, how come there's only a small amount of PGs doing backfill when we have such a large misplaced percentage? Can this be just from backfill reservation logjam? Mvh. Torkil -- Torkil Svensgaard Systems Administrator Danish Research Centre for Magnetic Resonance DRCMR, Section 714 Copenhagen University Hospital Amager and Hvidovre Kettegaard Allé 30, 2650 Hvidovre, Denmark