Kyle,
Was the cluster still backfilling when you removed osd 6 or did you only check its utilization?
Running an EC pool with m=1 is a bad idea. EC pool min_size = k+1 so losing a single OSD results in inaccessible data.
Your incomplete PG's are probably all EC pool pgs, please verify.
If the above statement is true, you could *temporarily* set min_size to 2 (on your EC pools) to get back access to your data again but this is a very dangerous action. Losing another OSD during this period results in actual data loss.
Kind regards,
Caspar Smit
Caspar Smit
Op vr 5 jul. 2019 om 01:17 schreef Kyle <aradian@xxxxxxxxx>:
Hello,
I'm working with a small ceph cluster (about 10TB, 7-9 OSDs, all Bluestore on
lvm) and recently ran into a problem with 17 pgs marked as incomplete after
adding/removing OSDs.
Here's the sequence of events:
1. 7 osds in the cluster, health is OK, all pgs are active+clean
2. 3 new osds on a new host are added, lots of backfilling in progress
3. osd 6 needs to be removed, so we do "ceph osd crush reweight osd.6 0"
4. after a few hours we see "min osd.6 with 0 pgs" from "ceph osd utilization"
5. ceph osd out 6
6. systemctl stop ceph-osd@6
7. the drive backing osd 6 is pulled and wiped
8. backfilling has now finished all pgs are active+clean except for 17
incomplete pgs
>From reading the docs, it sounds like there has been unrecoverable data loss
in those 17 pgs. That raises some questions for me:
Was "ceph osd utilization" only showing a goal of 0 pgs allocated instead of
the current actual allocation?
Why is there data loss from a single osd being removed? Shouldn't that be
recoverable?
All pools in the cluster are either replicated 3 or erasure-coded k=2,m=1 with
default "host" failure domain. They shouldn't suffer data loss with a single
osd being removed even if there were no reweighting beforehand. Does the
backfilling temporarily reduce data durability in some way?
Is there a way to see which pgs actually have data on a given osd?
I attached an example of one of the incomplete pgs.
Thanks for any help,
Kyle_______________________________________________
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