Marc <Marc@xxxxxxxxxxxxxxxxx> writes:
>> For the background: we have many Perc H800+MD1200 [1] systems running
>> with
>> 10TB HDDs (raid0, read ahead, writeback cache).
>> One server has LSI SAS3008 [0] instead of the Perc H800,
>> which comes with 512MB RAM + BBU. On most servers latencies are around
>> 4-12ms (average 6ms), on the system with the LSI controller we see
>> 20-60ms (average 30ms) latency.
>
> How did you get these latencies? Then I can show you maybe what I have with the SAS2308.
Via grafana->prometheus->ceph-mgr:
--------------------------------------------------------------------------------
avg by (hostname) (ceph_osd_apply_latency_ms{dc="$place"} * on
(ceph_daemon) group_left(hostname) ceph_osd_metadata{dc="$place"})
--------------------------------------------------------------------------------
where $place = the data center name. I cross checked the numbers with
the OSDs using
--------------------------------------------------------------------------------
ceph_osd_apply_latency_ms{dc="$place"}
--------------------------------------------------------------------------------
which showed that all OSDs attached to that controller are in a similar
range, so the average above is not hiding "one bad osd".
Does that help?
--
Sustainable and modern Infrastructures by ungleich.ch
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