Hi,
On 06/21/2018 05:14 AM, Dave.Chen@xxxxxxxx wrote:
Hi all,
I have setup a ceph cluster in my lab recently, the configuration per my understanding should be okay, 4 OSD across 3 nodes, 3 replicas, but couple of PG stuck with state "active+undersized+degraded", I think this should be very generic issue, could anyone help me out?
Here is the details about the ceph cluster,
$ ceph -v (jewel)
ceph version 10.2.10 (5dc1e4c05cb68dbf62ae6fce3f0700e4654fdbbe)
# ceph osd tree
ID WEIGHT TYPE NAME UP/DOWN REWEIGHT PRIMARY-AFFINITY
-1 5.89049 root default
-2 1.81360 host ceph3
2 1.81360 osd.2 up 1.00000 1.00000
-3 0.44969 host ceph4
3 0.44969 osd.3 up 1.00000 1.00000
-4 3.62720 host ceph1
0 1.81360 osd.0 up 1.00000 1.00000
1 1.81360 osd.1 up 1.00000 1.00000
*snipsnap*
You have a large difference in the capacities of the nodes. This results
in a different host weight, which in turn might lead to problems with
the crush algorithm. It is not able to get three different hosts for OSD
placement for some of the PGs.
CEPH and crush do not cope well with heterogenous setups. I would
suggest to move one of the OSDs from host ceph1 to ceph4 to equalize the
host weight.
Regards,
Burkhard
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