Hi,
We have recently added a new storage node to our Luminous (12.2.13)
cluster. The prev nodes are all setup as Filestore: e.g 12 osds on hdd
(Seagate Constellations) with one NVMe (Intel P4600) journal. With the
new guy we decided to introduce Bluestore so it is configured as: (same
HW) 12 osd with data on hdd and db + wal on one NVMe.
We noticed there are periodic slow requests logged, and the implicated
osds are the Bluestore ones 98% of the time! This suggests that we need
to tweak our Bluestore settings in some way. Investigating I'm seeing:
- A great deal of rocksdb debug info in the logs - perhaps we should
tone that down? (debug_rocksdb 4/5 -> 1/5)
- We look to have the default cache settings
(bluestore_cache_size_hdd|ssd etc), we have memory to increase these
- There are some buffered io settings (bluefs_buffered_io,
bluestore_default_buffered_write), set to (default) false. Are these
safe (or useful) to change?
- We have default rocksdb options, should some of these be changed?
(bluestore_rocksdb_options, in particular max_background_compactions=2 -
should we have less, or more?)
Also, anything else we should be looking at?
regards
Mark
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