On Fri, Apr 29, 2016 at 5:54 AM, Alexey Sheplyakov <asheplyakov@xxxxxxxxxxxx> wrote:
Hi,As far as I understand this can only harm your data. The acting set of PG 17.73 is [41, 148],
> i also wonder if just taking 148 out of the cluster (probably just marking it out) would help
so after stopping/taking out OSD 148 OSD 41 will store the only copy of objects in PG 17.73
(so it won't accept writes any more).
> since there are other osds in the up set (140 and 5)
These OSDs are not in the acting set, they have no (at least some of the) objects from PG 17.73,
and are copying the missing objects from OSDs 41 and 148. Naturally this slows down or even
blocks writes to PG 17.73.
k. i didn't know if it could just use the members of the up set that are not in the acting set for completing writes. when thinking through it in my head it seemed reasonable but i could also see pitfalls with doing it. thats why i was asking if it was possible.
> the only thing holding things together right now is a while loop doing an 'ceph osd down 41' every minuteAs far as I understand this disturbs the backfilling and further delays writes to that poor PG.
it definitely does seem to have an impact similar to that. the only upside is that it clears the slow io messages though i don't know if it actually lets the client io complete. recovery doesn't make any progress though in between the down commands. its not making any progress on its own anyways.
mike
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