[ceph-users] slow_used_bytes - SlowDB being used despite lots of space free in BlockDB on SSD?

Nick Fisk nick at fisk.me.uk
Thu Oct 18 09:49:51 PDT 2018


Hi,

Ceph Version = 12.2.8   
8TB spinner with 20G SSD partition 

Perf dump shows the following:

"bluefs": {
        "gift_bytes": 0,
        "reclaim_bytes": 0,
        "db_total_bytes": 21472731136,
        "db_used_bytes": 3467640832,
        "wal_total_bytes": 0,
        "wal_used_bytes": 0,
        "slow_total_bytes": 320063143936,
        "slow_used_bytes": 4546625536,
        "num_files": 124,
        "log_bytes": 11833344,
        "log_compactions": 4,
        "logged_bytes": 316227584,
        "files_written_wal": 2,
        "files_written_sst": 4375,
        "bytes_written_wal": 204427489105,
        "bytes_written_sst": 248223463173

Am I reading that correctly, about 3.4GB used out of 20GB on the SSD, yet 4.5GB of DB is stored on the spinning disk?

Am I also understanding correctly that BlueFS has reserved 300G of space on the spinning disk?

Found a previous bug tracker for something which looks exactly the same case, but should be fixed now:
https://tracker.ceph.com/issues/22264

Thanks,
Nick



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