Hi Ingo,
If you are able and have lots of available memory, could you also try
setting it to false but increasing the osd_memory_target size? I'd like
to understand a little bit deeper what's going on here. Ultimately I
don't want our only line of defense against slow snap trimming to be
having page cache available!
Mark
On 8/7/20 6:51 AM, Ingo Reimann wrote:
Hi Stefan, Hi Manuel,
thanks for your quick advices.
In fact, since i set "ceph config set osd bluefs_buffered_io true", the problems disappeared. We have lots of RAM in our osd hosts, so buffering is ok. I`ll trak this issue down further after the weekend!
best regards,
Ingo
----- Ursprüngliche Mail -----
Von: "Stefan Kooman" <stefan@xxxxxx>
An: "ceph-users" <ceph-users@xxxxxxx>
Gesendet: Freitag, 7. August 2020 12:24:08
Betreff: Re: OSDs flapping since upgrade to 14.2.10
On 2020-08-07 12:07, Ingo Reimann wrote:
i`m am not sure, if we really have a problem, but it does not look healthy.
It might be related to the change that is mentioned in another thread:
"block.db/block.wal device performance dropped after upgrade to 14.2.10"
TL;DR: bluefs_buffered_io has been changed to "false" in 14.2.10. It
doesn't use buffer cache in that case, and in certain workloads (i.e.
snap trimming) this seem to have a big impact, even for environments
that have large osd_memory_target.
I would change that back to "true" ("ceph config set osd
bluefs_buffered_io true" should do the trick). Not sure if the OSDs need
a restart afterwards, as the config change seem to be effectve
immediately for running daemons.
Gr. Stefan
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