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Hi
The "ec unable to recover when below min size" thing has very recently been fixed for octopus.
See https://tracker.ceph.com/issues/18749 and https://github.com/ceph/ceph/pull/17619
Docs has been updated with a section on this issue http://docs.ceph.com/docs/master/rados/operations/erasure-code/#erasure-coded-pool-recover
/Torben
On 05.07.2019 11:50, Paul Emmerich wrote:
* There are virtually no use cases for ec pools with m=1, this is a bad configuration as you can't have both availability and durability
* Due to weird internal restrictions ec pools below their min size can't recover, you'll probably have to reduce min_size temporarily to recover it
* Depending on your version it might be necessary to restart some of the OSDs due to a bug (fixed by now) that caused it to mark some objects as degraded if you remove or restart an OSD while you have remapped objects
* run "ceph osd safe-to-destroy X" to check if it's safe to destroy a given OSD
-- Paul Emmerich Looking for help with your Ceph cluster? Contact us at https://croit.iocroit GmbH Freseniusstr. 31h 81247 München www.croit.ioTel: +49 89 1896585 90
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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