AFAIR, there is a feature request in the works to allow rebuild with K
chunks, but not allow normal read/write until min_size is met. Not
that I think running with m=1 is a good idea. I'm not seeing the
tracker issue for it at the moment, though.
--
Adam
On Tue, Dec 11, 2018 at 9:50 PM Ashley Merrick <singapore@xxxxxxxxxxxxxx> wrote:
>
> Yes if you set back to 5, every time your loose an OSD your have to set to 4 and let the rebuild take place before putting back to 5.
>
> I guess is all down to how important 100% up time is over you manually monitoring the back fill / fix the OSD / replace the OSD by dropping to 4 vs letting it do this automatically and risk a further OSD loss.
>
> If you have the space ID suggest going to 4 + 2 and migrating your data, this would remove the ongoing issue and give you some extra data protection from OSD loss.
>
> On Wed, Dec 12, 2018 at 11:43 AM David Young <funkypenguin@xxxxxxxxxxxxxx> wrote:
>>
>> (accidentally forgot to reply to the list)
>>
>> Thank you, setting min_size to 4 allowed I/O again, and the 39 incomplete PGs are now:
>>
>> 39 active+undersized+degraded+remapped+backfilling
>>
>> Once backfilling is done, I'll increase min_size to 5 again.
>>
>> Am I likely to encounter this issue whenever I loose an OSD (I/O freezes and manually reducing size is required), and is there anything I should be doing differently?
>>
>> Thanks again!
>> D
>>
>>
>>
>> Sent with ProtonMail Secure Email.
>>
>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>> On Wednesday, December 12, 2018 3:31 PM, Ashley Merrick <singapore@xxxxxxxxxxxxxx> wrote:
>>
>> With EC the min size is set to K + 1.
>>
>> Generally EC is used with a M of 2 or more, reason min size is set to 1 is now you are in a state when a further OSD loss will cause some PG’s to not have at least K size available as you only have 1 extra M.
>>
>> As per the error you can get your pool back online by setting min_size to 4.
>>
>> However this would only be a temp fix while you get the OSD back online / rebuilt so you can go back to your 4 + 1 state.
>>
>> ,Ash
>>
>> On Wed, 12 Dec 2018 at 10:27 AM, David Young <funkypenguin@xxxxxxxxxxxxxx> wrote:
>>>
>>> Hi all,
>>>
>>> I have a small 2-node cluster with 40 OSDs, using erasure coding 4+1
>>>
>>> I lost osd38, and now I have 39 incomplete PGs.
>>>
>>> ---
>>> PG_AVAILABILITY Reduced data availability: 39 pgs inactive, 39 pgs incomplete
>>> pg 22.2 is incomplete, acting [19,33,10,8,29] (reducing pool media min_size from 5 may help; search ceph.com/docs for 'incomplete')
>>> pg 22.f is incomplete, acting [17,9,23,14,15] (reducing pool media from 5 may help; search ceph.com/docs for 'incomplete')
>>> pg 22.12 is incomplete, acting [7,33,10,31,29] (reducing pool media min_size from 5 may help; search ceph.com/docs for 'incomplete')
>>> pg 22.13 is incomplete, acting [23,0,15,33,13] (reducing pool media min_size from 5 may help; search ceph.com/docs for 'incomplete')
>>> pg 22.23 is incomplete, acting [29,17,18,15,12] (reducing pool media min_size from 5 may help; search ceph.com/docs for 'incomplete')
>>> <snip>
>>> ---
>>>
>>> My EC profile is below:
>>>
>>> ---
>>> root@prod1:~# ceph osd erasure-code-profile get ec-41-profile
>>> crush-device-class=
>>> crush-failure-domain=osd
>>> crush-root=default
>>> jerasure-per-chunk-alignment=false
>>> k=4
>>> m=1
>>> plugin=jerasure
>>> technique=reed_sol_van
>>> w=8
>>> ---
>>>
>>> When I query one of the incomplete PGs, I see this:
>>>
>>> ---
>>> "recovery_state": [
>>> {
>>> "name": "Started/Primary/Peering/Incomplete",
>>> "enter_time": "2018-12-11 20:46:11.645796",
>>> "comment": "not enough complete instances of this PG"
>>> },
>>> ---
>>>
>>> And this:
>>>
>>> ---
>>> "probing_osds": [
>>> "0(4)",
>>> "7(2)",
>>> "9(1)",
>>> "11(4)",
>>> "22(3)",
>>> "29(2)",
>>> "36(0)"
>>> ],
>>> "down_osds_we_would_probe": [
>>> 38
>>> ],
>>> "peering_blocked_by": []
>>> },
>>> ---
>>>
>>> I have set this in /etc/ceph/ceph.conf to no effect:
>>> osd_find_best_info_ignore_history_les = true
>>>
>>>
>>> As a result of the incomplete PGs, I/O is currently frozen to at last part of my cephfs.
>>>
>>> I expected to be able to tolerate the loss of an OSD without issue, is there anything I can do to restore these incomplete PGs?
>>>
>>> When I bring back a new osd38, I see:
>>> ---
>>> "probing_osds": [
>>> "4(2)",
>>> "11(3)",
>>> "22(1)",
>>> "24(1)",
>>> "26(2)",
>>> "36(4)",
>>> "38(1)",
>>> "39(0)"
>>> ],
>>> "down_osds_we_would_probe": [],
>>> "peering_blocked_by": []
>>> },
>>> {
>>> "name": "Started",
>>> "enter_time": "2018-12-11 21:06:35.307379"
>>> }
>>> ---
>>>
>>> But my recovery state is still:
>>>
>>> ---
>>> "recovery_state": [
>>> {
>>> "name": "Started/Primary/Peering/Incomplete",
>>> "enter_time": "2018-12-11 21:06:35.320292",
>>> "comment": "not enough complete instances of this PG"
>>> },
>>> ---
>>>
>>> Any ideas?
>>>
>>> Thanks!
>>> D
>>>
>>> _______________________________________________
>>> ceph-users mailing list
>>> ceph-users@xxxxxxxxxxxxxx
>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>>
>>
>>
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