min_size in the crush rule and min_size in the pool are completely
different things that happen to share the same name.
Ignore min_size in the crush rule, it has virtually no meaning in
almost all cases (like this one).
Paul
--
Paul Emmerich
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On Mon, Jan 27, 2020 at 3:41 PM Smith, Eric <Eric.Smith(a)ccur.com> wrote:
>
> I have a Ceph Luminous (12.2.12) cluster with 6 nodes. I’m attempting to create an
EC3+2 pool with the following commands:
>
> Create the EC profile:
>
> ceph osd erasure-code-profile set es32 k=3 m=2 plugin=jerasure w=8
technique=reed_sol_van crush-failure-domain=host crush-root=sgshared
>
> Verify profile creation:
>
> [root@mon-1 ~]# ceph osd erasure-code-profile get es32
>
> crush-device-class=
>
> crush-failure-domain=host
>
> crush-root=sgshared
>
> jerasure-per-chunk-alignment=false
>
> k=3
>
> m=2
>
> plugin=jerasure
>
> technique=reed_sol_van
>
> w=8
>
> Create a pool using this profile:
>
> ceph osd pool create ec32pool 1024 1024 erasure es32
>
> List pool detail:
>
> pool 31 'es32' erasure size 5 min_size 4 crush_rule 11 object_hash rjenkins
pg_num 1024 pgp_num 1024 last_change 1568 flags hashpspool stripe_width 12288 application
ES
>
> Here’s the crush rule that’s created:
> {
>
> "rule_id": 11,
>
> "rule_name": "es32",
>
> "ruleset": 11,
>
> "type": 3,
>
> "min_size": 3,
>
> "max_size": 5,
>
> "steps": [
>
> {
>
> "op": "set_chooseleaf_tries",
>
> "num": 5
>
> },
>
> {
>
> "op": "set_choose_tries",
>
> "num": 100
>
> },
>
> {
>
> "op": "take",
>
> "item": -2,
>
> "item_name": "sgshared"
>
> },
>
> {
>
> "op": "chooseleaf_indep",
>
> "num": 0,
>
> "type": "host"
>
> },
>
> {
>
> "op": "emit"
>
> }
>
> ]
>
> },
>
>
>
> From the output of “ceph osd pool ls detail” you can see min_size=4, the crush rule
says min_size=3 however the pool does NOT survive 2 hosts failing.
>
>
>
> Am I missing something?
>
>
>
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