Even I faced the same issue with our production cluster .
cluster fac04d85-db48-4564-b821-deebda046261
health HEALTH_WARN
658 pgs degraded
658 pgs stuck degraded
688 pgs stuck unclean
658 pgs stuck undersized
658 pgs undersized
recovery 3064/1981308 objects degraded (0.155%)
recovery 124/1981308 objects misplaced (0.006%)
monmap e11: 11 mons at
{dssmon2=10.140.208.224:6789/0,dssmon3=10.140.208.225:6789/0,dssmon31=10.135.38.141:6789/0,dssmon32=10.135.38.142:6789/0,dssmon33=10.135.38.143:6789/0,dssmon34=10.135.38.144:6789/0,dssmon35=10.135.38.145:6789/0,dssmon4=10.140.208.226:6789/0,dssmon5=10.140.208.227:6789/0,dssmon6=10.140.208.228:6789/0,dssmonleader1=10.140.208.223:6789/0}
election epoch 792, quorum 0,1,2,3,4,5,6,7,8,9,10
dssmon31,dssmon32,dssmon33,dssmon34,dssmon35,dssmonleader1,dssmon2,dssmon3,dssmon4,dssmon5,dssmon6
osdmap e8778: 2774 osds: 2746 up, 2746 in; 30 remapped pgs
pgmap v2740957: 75680 pgs, 11 pools, 386 GB data, 322 kobjects
16288 GB used, 14299 TB / 14315 TB avail
3064/1981308 objects degraded (0.155%)
124/1981308 objects misplaced (0.006%)
74992 active+clean
658 active+undersized+degraded
30 active+remapped
client io 12394 B/s rd, 17 op/s
With 12 osd are down due to H/W failure, and having replication factor
6 , the cluster should have recovered , but it is not recovering.
When I kill an osd daemon, it recovers quickly. Any ideas why the PGs
are remaining undersized ?
What could be the difference between two scenarions :
1. OSD down due to H/W failure.
2. OSD daemon killed .
When I remove the 12 osds from the crushmap manually or do ceph osd
crush remove for those osds, the cluster recovers just fine.
Thanks
Gaurav
On Tue, May 17, 2016 at 2:08 AM, Wido den Hollander <wido@xxxxxxxx> wrote:
>
>> Op 14 mei 2016 om 12:36 schreef Lazuardi Nasution <mrxlazuardin@xxxxxxxxx>:
>>
>>
>> Hi Wido,
>>
>> Yes you are right. After removing the down OSDs, reformatting and bring
>> them up again, at least until 75% of total OSDs, my Ceph Cluster is healthy
>> again. It seem there is high probability of data safety if the total active
>> PGs same with total PGs and total degraded PGs same with total undersized
>> PGs, but it is better to check PGs one by one for make sure there is no
>> incomplete, unfound and/or missing objects.
>>
>> Anyway, why 75%? Can I reduce this value by resizing (add) the replica of
>> the pool?
>>
>
> It completely depends on the CRUSHMap how many OSDs have to be added back to allow the cluster to recover.
>
> A CRUSHmap has failure domains which is usually a host. You have to make sure you have enough 'hosts' online with OSDs for each replica.
>
> So with 3 replicas you need 3 hosts online with OSDs on there.
>
> You can lower the replica count of a pool (size), but that makes it more vulnerable to data loss.
>
> Wido
>
>> Best regards,
>>
>> On Fri, May 13, 2016 at 5:04 PM, Wido den Hollander <wido@xxxxxxxx> wrote:
>>
>> >
>> > > Op 13 mei 2016 om 11:55 schreef Lazuardi Nasution <
>> > mrxlazuardin@xxxxxxxxx>:
>> > >
>> > >
>> > > Hi Wido,
>> > >
>> > > The status is same after 24 hour running. It seem that the status will
>> > not
>> > > go to fully active+clean until all down OSDs back again. The only way to
>> > > make down OSDs to go back again is reformating or replace if HDDs has
>> > > hardware issue. Do you think that it is safe way to do?
>> > >
>> >
>> > Ah, you are probably lacking enough replicas to make the recovery proceed.
>> >
>> > If that is needed I would do this OSD by OSD. Your crushmap will probably
>> > tell you which OSDs you need to bring back before it works again.
>> >
>> > Wido
>> >
>> > > Best regards,
>> > >
>> > > On Fri, May 13, 2016 at 4:44 PM, Wido den Hollander <wido@xxxxxxxx>
>> > wrote:
>> > >
>> > > >
>> > > > > Op 13 mei 2016 om 11:34 schreef Lazuardi Nasution <
>> > > > mrxlazuardin@xxxxxxxxx>:
>> > > > >
>> > > > >
>> > > > > Hi,
>> > > > >
>> > > > > After disaster and restarting for automatic recovery, I found
>> > following
>> > > > > ceph status. Some OSDs cannot be restarted due to file system
>> > corruption
>> > > > > (it seem that xfs is fragile).
>> > > > >
>> > > > > [root@management-b ~]# ceph status
>> > > > > cluster 3810e9eb-9ece-4804-8c56-b986e7bb5627
>> > > > > health HEALTH_WARN
>> > > > > 209 pgs degraded
>> > > > > 209 pgs stuck degraded
>> > > > > 334 pgs stuck unclean
>> > > > > 209 pgs stuck undersized
>> > > > > 209 pgs undersized
>> > > > > recovery 5354/77810 objects degraded (6.881%)
>> > > > > recovery 1105/77810 objects misplaced (1.420%)
>> > > > > monmap e1: 3 mons at {management-a=
>> > > > >
>> > > >
>> > 10.255.102.1:6789/0,management-b=10.255.102.2:6789/0,management-c=10.255.102.3:6789/0
>> > > > > }
>> > > > > election epoch 2308, quorum 0,1,2
>> > > > > management-a,management-b,management-c
>> > > > > osdmap e25037: 96 osds: 49 up, 49 in; 125 remapped pgs
>> > > > > flags sortbitwise
>> > > > > pgmap v9024253: 2560 pgs, 5 pools, 291 GB data, 38905 objects
>> > > > > 678 GB used, 90444 GB / 91123 GB avail
>> > > > > 5354/77810 objects degraded (6.881%)
>> > > > > 1105/77810 objects misplaced (1.420%)
>> > > > > 2226 active+clean
>> > > > > 209 active+undersized+degraded
>> > > > > 125 active+remapped
>> > > > > client io 0 B/s rd, 282 kB/s wr, 10 op/s
>> > > > >
>> > > > > Since total active PGs same with total PGs and total degraded PGs
>> > same
>> > > > with
>> > > > > total undersized PGs, does it mean that all PGs have at least one
>> > good
>> > > > > replica, so I can just mark lost or remove down OSD, reformat again
>> > and
>> > > > > then restart them if there is no hardware issue with HDDs? Which one
>> > of
>> > > > PGs
>> > > > > status should I pay more attention, degraded or undersized due to
>> > lost
>> > > > > object possibility?
>> > > > >
>> > > >
>> > > > Yes. Your system is not reporting any inactive, unfound or stale PGs,
>> > so
>> > > > that is good news.
>> > > >
>> > > > However, I recommend that you wait for the system to become fully
>> > > > active+clean before you start removing any OSDs or formatting hard
>> > drives.
>> > > > Better be safe than sorry.
>> > > >
>> > > > Wido
>> > > >
>> > > > > Best regards,
>> > > > > _______________________________________________
>> > > > > ceph-users mailing list
>> > > > > ceph-users@xxxxxxxxxxxxxx
>> > > > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>> > > >
>> >
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--
Gaurav Bafna
9540631400
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