Hi Frank,
I think you need at least 6 OSD hosts to make EC 4+2 with faillure domain host.
I do not know how it was possible for you to create that configuration at
first?
Could it be that you have multiple name for the OSD hosts?
That would at least explain the one OSD down, being show as two OSDs down.
Also, I believe that min_size should never be smaller than “coding” shards,
which is 4 in this case.
You can either make a new test setup with your three test OSD hosts using EC
2+1 or make e.g. 4+2, but with failure domain set to OSD.
Best,
Jesper
--------------------------
Jesper Lykkegaard Karlsen
Scientific Computing
Centre for Structural Biology
Department of Molecular Biology and Genetics
Aarhus University
Universitetsbyen 81
8000 Aarhus C
E-mail: je...@mbg.au.dk
Tlf: +45 50906203
> On 27 Jul 2022, at 17.32, Frank Schilder <fr...@dtu.dk> wrote:
>
> Update: the inactive PG got recovered and active after a loooonngg wait. The
> middle question is now answered. However, these two questions are still of
> great worry:
>
> - How can 2 OSDs be missing if only 1 OSD is down?
> - If the PG should recover, why is it not prioritised considering its severe
> degradation
> compared with all other PGs?
>
> I don't understand how a PG can loose 2 shards if 1 OSD goes down. That looks
> really really bad to me (did ceph loose track of data??).
>
> The second is of no less importance. The inactive PG was holding back client
> IO, leading to further warnings about slow OPS/requests/... Why are such
> critically degraded PGs not scheduled for recovery first? There is a service
> outage but only a health warning?
>
> Thanks and best regards.
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
>
> ________________________________________
> From: Frank Schilder <fr...@dtu.dk>
> Sent: 27 July 2022 17:19:05
> To: ceph-users@ceph.io
> Subject: [ceph-users] PG does not become active
>
> I'm testing octopus 15.2.16 and run into a problem right away. I'm filling up
> a small test cluster with 3 hosts 3x3 OSDs and killed one OSD to see how
> recovery works. I have one 4+2 EC pool with failure domain host and on 1 PGs
> of this pool 2 (!!!) shards are missing. This most degraded PG is not
> becoming active, its stuck inactive but peered.
>
> Questions:
>
> - How can 2 OSDs be missing if only 1 OSD is down?
> - Wasn't there an important code change to allow recovery for an EC PG with at
> least k shards present even if min_size>k? Do I have to set something?
> - If the PG should recover, why is it not prioritised considering its severe
> degradation
> compared with all other PGs?
>
> I have already increased these crush tunables and executed a pg repeer to no
> avail:
>
> tunable choose_total_tries 250 <-- default 100
> rule fs-data {
> id 1
> type erasure
> min_size 3
> max_size 6
> step set_chooseleaf_tries 50 <-- default 5
> step set_choose_tries 200 <-- default 100
> step take default
> step choose indep 0 type osd
> step emit
> }
>
> Ceph health detail says to that:
>
> [WRN] PG_AVAILABILITY: Reduced data availability: 1 pg inactive
> pg 4.32 is stuck inactive for 37m, current state
> recovery_wait+undersized+degraded+remapped+peered, last acting
> [1,2147483647,2147483647,4,5,2]
>
> I don't want to cheat and set min_size=k on this pool. It should work by
> itself.
>
> Thanks for any pointers!
> =================
> Frank Schilder
> AIT Risø Campus
> Bygning 109, rum S14
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