[ceph-users] Ceph 16.2.x mon compactions, disk writes

Hi, Monitors in our 16.2.14 cluster appear to quite often run "manual compaction" tasks: debug 2023-10-09T09:30:53.888+0000 7f48a329a700 4 rocksdb: EVENT_LOG_v1 {"time_micros": 1696843853892760, "job": 64225, "event": "flush_started", "num_memtables": 1, "num_entries": 715, "num_deletes": 251, "total_data_size": 3870352, "memory_usage": 3886744, "flush_reason": "Manual Compaction"} debug 2023-10-09T09:30:53.904+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:30:53.910204) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-0 to level-5 from 'paxos .. 'paxos; will stop at (end) debug 2023-10-09T09:30:53.908+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:30:53.908+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:30:53.911004) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-5 to level-6 from 'paxos .. 'paxos; will stop at (end) debug 2023-10-09T09:32:08.956+0000 7f48a329a700 4 rocksdb: EVENT_LOG_v1 {"time_micros": 1696843928961390, "job": 64228, "event": "flush_started", "num_memtables": 1, "num_entries": 1580, "num_deletes": 502, "total_data_size": 8404605, "memory_usage": 8465840, "flush_reason": "Manual Compaction"} debug 2023-10-09T09:32:08.972+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:32:08.977739) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-0 to level-5 from 'logm .. 'logm; will stop at (end) debug 2023-10-09T09:32:08.976+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:08.976+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:32:08.978512) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-5 to level-6 from 'logm .. 'logm; will stop at (end) debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:32:12.764+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.028+0000 7f48a329a700 4 rocksdb: EVENT_LOG_v1 {"time_micros": 1696844009033151, "job": 64231, "event": "flush_started", "num_memtables": 1, "num_entries": 1430, "num_deletes": 251, "total_data_size": 8975535, "memory_usage": 9035920, "flush_reason": "Manual Compaction"} debug 2023-10-09T09:33:29.044+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:33:29.049585) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-0 to level-5 from 'paxos .. 'paxos; will stop at (end) debug 2023-10-09T09:33:29.048+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f4899286700 4 rocksdb: [db_impl/db_impl_compaction_flush.cc:1443] [default] Manual compaction starting debug 2023-10-09T09:33:29.048+0000 7f48a3a9b700 4 rocksdb: (Original Log Time 2023/10/09-09:33:29.050355) [db_impl/db_impl_compaction_flush.cc:2516] [default] Manual compaction from level-5 to level-6 from 'paxos .. 'paxos; will stop at (end) I have removed a lot of interim log messages to save space. During each compaction the monitor process writes approximately 500-600 MB of data to disk over a short period of time. These writes add up to tens of gigabytes per hour and hundreds of gigabytes per day. Monitor rocksdb and compaction options are default: "mon_compact_on_bootstrap": "false", "mon_compact_on_start": "false", "mon_compact_on_trim": "true", "mon_rocksdb_options": "write_buffer_size=33554432,compression=kNoCompression,level_compaction_dynamic_level_bytes=true", Is this expected behavior? Is this something I can adjust in order to extend the system storage life? Best regards, Zakhar