CephNotes

Some notes about Ceph
Laurent Barbe @Adelius / INRAE

Ceph Journal Migration

An exemple for migrating journal from file on the default location to a dedicated partition on /dev/sde1.

$ apt-get install hdparm

### Stop osd
$ service ceph stop osd.0

### Flush Journal
$ ceph-osd --flush-journal -i 0

### Create symlink to partition
$ rm /var/lib/ceph/osd/ceph-0/journal
$ ln -s /dev/sde1 /var …

Ceph Versions

6 months since my last post... Firefly is released. http://ceph.com/releases/v0-80-firefly-released/

Ceph Major Release

Version Date Some new features
0.87 - Giant 11/2014 http://ceph.com/uncategorized/v0-87-giant-released/
0.80 - Firefly 07/2014 erasure coding, cache tiering
0.72 - Emperor 11/2013 multi-datacenter replication RGW, improved …

Feature set mismatch error on Ceph kernel client

Depending on the kernel version you may be missing some features required by the cluster (or vice versa, required by client but not available on the cluster). Hence the errors "feature set mismatch".

Some examples of errors that can be encountered :

mon0 192.168.0.1:6789 feature set mismatch …

Set tunables optimal on Ceph crushmap

Il you just upgrade to Ceph 0.75, you can see this message :

$ ceph health HEALTH_WARN crush map has non-optimal tunables

For more explanation, everything is explained in the documentation: http://ceph.com/docs/master/rados/operations/crush-map/#warning-when-tunables-are-non-optimal

Before doing this, read the documentation !

$ ceph osd crush tunables optimal …

RBD client kernel 3.10.26

I take opportunity to the new kernel release 3.10.26 to advise the person using the client rbd kernel update to this version. Indeed a number of fixes have been applied to this version making use of rbd kernel particularly stable.

http://kernel.org

Patches applied :

Josh Durgin <josh …