26 Jun
2020
26 Jun
'20
10:59 a.m.
From my point of view, it's better to have no more than 6 osd wal/db on 1
nvme.
I think that's the root cause of the slow requests, maybe.
Mark Kirkwood <mark.kirkwood(a)catalyst.net.nz> 于2020年6月26日周五 上午7:47写道：
Progress update:
- tweaked debug_rocksdb to 1/5. *possibly* helped, fewer slow requests
- will increase osd_memory_target from 4 to 16G, and observe
On 24/06/20 1:30 pm, Mark Kirkwood wrote:
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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