[ceph-users] Disk Down Emergency

Caspar Smit casparsmit at supernas.eu
Thu Nov 16 05:23:16 PST 2017


2017-11-16 14:05 GMT+01:00 Georgios Dimitrakakis <giorgis at acmac.uoc.gr>:

> Dear cephers,
>
> I have an emergency on a rather small ceph cluster.
>
> My cluster consists of 2 OSD nodes with 10 disks x4TB each and 3 monitor
> nodes.
>
> The version of ceph running is Firefly v.0.80.9
> (b5a67f0e1d15385bc0d60a6da6e7fc810bde6047)
>
> The cluster originally was build with "Replicated size=2" and "Min size=1"
> with the attached crush map,
> which in my understanding this replicates data across hosts.
>
> The emergency comes from the violation of the golden rule: "Never use 2
> replicas on a production cluster"
>
> Unfortunately the customers never really understood well the risk and now
> that one disk is down I am in the middle and I must do everything in my
> power not to loose any data, thus I am requesting your assistance.
>
> Here is the output of
>
> $ ceph osd tree
> # id    weight  type name       up/down reweight
> -1      72.6    root default
> -2      36.3            host store1
> 0       3.63                    osd.0   down    0       ---> DISK DOWN
> 1       3.63                    osd.1   up      1
> 2       3.63                    osd.2   up      1
> 3       3.63                    osd.3   up      1
> 4       3.63                    osd.4   up      1
> 5       3.63                    osd.5   up      1
> 6       3.63                    osd.6   up      1
> 7       3.63                    osd.7   up      1
> 8       3.63                    osd.8   up      1
> 9       3.63                    osd.9   up      1
> -3      36.3            host store2
> 10      3.63                    osd.10  up      1
> 11      3.63                    osd.11  up      1
> 12      3.63                    osd.12  up      1
> 13      3.63                    osd.13  up      1
> 14      3.63                    osd.14  up      1
> 15      3.63                    osd.15  up      1
> 16      3.63                    osd.16  up      1
> 17      3.63                    osd.17  up      1
> 18      3.63                    osd.18  up      1
> 19      3.63                    osd.19  up      1
>
> and here is the status of the cluster
>
>
> # ceph health
> HEALTH_WARN 497 pgs degraded; 549 pgs stuck unclean; recovery
> 51916/2552684 objects degraded (2.034%)
>
>
> Althoug OSD.0 is shown as mounted it cannot be started (probably failed
> disk controller problem)
>
> # df -h
> Filesystem      Size  Used Avail Use% Mounted on
> /dev/sda3       251G  4.1G  235G   2% /
> tmpfs            24G     0   24G   0% /dev/shm
> /dev/sda1       239M  100M  127M  44% /boot
> /dev/sdj1       3.7T  223G  3.5T   6% /var/lib/ceph/osd/ceph-8
> /dev/sdh1       3.7T  205G  3.5T   6% /var/lib/ceph/osd/ceph-6
> /dev/sdg1       3.7T  199G  3.5T   6% /var/lib/ceph/osd/ceph-5
> /dev/sde1       3.7T  180G  3.5T   5% /var/lib/ceph/osd/ceph-3
> /dev/sdi1       3.7T  187G  3.5T   6% /var/lib/ceph/osd/ceph-7
> /dev/sdf1       3.7T  193G  3.5T   6% /var/lib/ceph/osd/ceph-4
> /dev/sdd1       3.7T  212G  3.5T   6% /var/lib/ceph/osd/ceph-2
> /dev/sdk1       3.7T  210G  3.5T   6% /var/lib/ceph/osd/ceph-9
> /dev/sdb1       3.7T  164G  3.5T   5% /var/lib/ceph/osd/ceph-0    --->
> This is the problematic OSD
> /dev/sdc1       3.7T  183G  3.5T   5% /var/lib/ceph/osd/ceph-1
>
>
>
> # service ceph start osd.0
> find: `/var/lib/ceph/osd/ceph-0': Input/output error
> /etc/init.d/ceph: osd.0 not found (/etc/ceph/ceph.conf defines mon.store1
> osd.6 osd.9 osd.1 osd.4 osd.3 osd.2 osd.8 osd.5 osd.7 mds.store1
> mon.store3, /var/lib/ceph defines mon.store1 osd.6 osd.9 osd.1 osd.4 osd.3
> osd.2 osd.8 osd.5 osd.7 mds.store1)
>
>
> I have found this: http://ceph.com/geen-categorie/admin-guide-replacing-a-
> failed-disk-in-a-ceph-cluster/
>
> and I am looking for your guidance in order to properly perform all
> actions in order not to loose any data and keep the ones of the second copy.
>
>
What guidance are you looking for besides the steps to replace a failed
disk (which you already found) ?
If i look at your situation, there is nothing 'down' in terms of
availability of pgs, just a failed drive which needs to be replaced.

Is the cluster still recovering? It should reach HEALTH_OK again after
rebalancing the cluster when an OSD goes down.

If it stopped recovering it might have to do with the ceph 'tunables' which
are not set to optimal by default on firefly and that prevents further
rebalancing.
WARNING: Don't just set tunables to optimal because it will trigger a
massive rebalance!

Perhaps the second golden rule is to never run a CEPH production cluster
without knowing (and testing) how to replace a failed drive. (I'm not
trying to be harsh here).

Kind regards,
Caspar


>
> Best regards,
>
> G.
> _______________________________________________
> ceph-users mailing list
> ceph-users at lists.ceph.com
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ceph.com/pipermail/ceph-users-ceph.com/attachments/20171116/94963e6b/attachment.html>


More information about the ceph-users mailing list