Quoting vitalif@yourcmc.ru (vitalif@yourcmc.ru):
SSD (block.db) partition contains object metadata in RocksDB so it probably loads the metadata before modifying objects (if it's not in cache yet). Also it sometimes performs compaction which also results in disk reads and writes. There are other things going on that I'm not completely aware of. There's the RBD object map... Maybe there are some locks that come into action when you parallel writes...
There's a config option to enable RocksDB performance counters. You can have a look into it.
Do you mean more info than: "rocksdb": { "rocksdb_write_wal_time": { "rocksdb_write_memtable_time": { "rocksdb_write_delay_time": { "rocksdb_write_pre_and_post_time": { I see a config option "rocksdb_perf", which is "false" (default config). Should this be changed to "true" to enable more RocksDB metrics? Thanks, Stefan -- | BIT BV https://www.bit.nl/ Kamer van Koophandel 09090351 | GPG: 0xD14839C6 +31 318 648 688 / info@bit.nl