[ceph-users] osd/bluestore: Get block.db usage

Wido den Hollander wido at 42on.com
Mon Dec 4 04:21:42 PST 2017


> Op 4 december 2017 om 13:10 schreef Hans van den Bogert <hansbogert at gmail.com>:
> 
> 
> Hi all,
> 
> Is there a way to get the current usage of the bluestore's block.db?
> I'd really like to monitor this as we have a relatively high number of
> objects per OSD.
> 

Yes, using 'perf dump':

root at bravo:~# ceph daemon osd.1 perf dump|jq '.bluefs'
{
  "gift_bytes": 0,
  "reclaim_bytes": 0,
  "db_total_bytes": 1073741824,
  "db_used_bytes": 33554432,
  "wal_total_bytes": 0,
  "wal_used_bytes": 0,
  "slow_total_bytes": 0,
  "slow_used_bytes": 0,
  "num_files": 9,
  "log_bytes": 15745024,
  "log_compactions": 0,
  "logged_bytes": 6279168,
  "files_written_wal": 1,
  "files_written_sst": 2,
  "bytes_written_wal": 5535337,
  "bytes_written_sst": 792836
}
root at bravo:~#

This cluster is just a test (you might remember it ;) ) and not running with any data at the moment.

'db_used_bytes' tells you how many bytes there are in the DB of BlueStore.

> A second question related to the above, are there mechanisms to
> influence which objects' metadata gets spilled once the block.db is
> full? -- For instance, I could not care for the extra latency when
> object metadata gets spilled to the backing disk if it for RGW-related
> data, in contrast to RBD objects metadata, which should remain on the
> faster SSD-based block.db.
> 

Not that I'm aware of.

Wido

> Regards,
> 
> Hans
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