[ceph-users] [Bluestore] Some of my osd's uses BlueFS slow storage for db - why?

Konstantin Shalygin k0ste at k0ste.ru
Sun Mar 17 20:58:25 PDT 2019


> Yes, I was in a similar situation initially where I had deployed my OSD's with 25GB DB partitions and after 3GB DB used, everything else was going into slowDB on disk. From memory 29GB was just enough to make the DB fit on flash, but 30GB is a safe round figure to aim for. With a 30GB DB partition with most RBD type workloads all data should reside on flash even for fairly large disks running erasure coding.
>
> Nick

Nick, thank you! After upgrading to 12.2.11 I was expand blockDB and for 
a week after compaction slowDB is not used [1].


{
   "gift_bytes": 0,
   "reclaim_bytes": 0,
   "db_total_bytes": 32212897792,
   "db_used_bytes": 6572474368,
   "wal_total_bytes": 1074589696,
   "wal_used_bytes": 528482304,
   "slow_total_bytes": 240043163648,
   "slow_used_bytes": 0,
   "num_files": 113,
   "log_bytes": 8683520,
   "log_compactions": 3,
   "logged_bytes": 203821056,
   "files_written_wal": 2,
   "files_written_sst": 1138,
   "bytes_written_wal": 121626085396,
   "bytes_written_sst": 47053353874
}

I also writed how-to increase partition size for my case, will maybe 
useful for someone [2].

[1] https://ibb.co/tXGqbbt

[2] https://bit.ly/2UFVO9Z

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