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+backfillingOnce 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!DSent 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.,AshOn 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!
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