Some notes about Ceph
Laurent Barbe @SIB

RBD journal offloading

If you are using rbd journaling feature (for example for rbd mirroring), in some cases it could be interesting to offloading journaling on specific pool. For example if your rbd pool is on hdd drives and you also have ssd or nvme.

external rbd journal

To change rbd journaling pool, there are 2 …

How many mouvement when I add a replica ?

Make a simple simulation !

Use your own crushmap :

$ ceph osd getcrushmap -o crushmap

got crush map from osdmap epoch 28673

Or create a sample clushmap :

$ crushtool --outfn crushmap --build --num_osds 36 host straw 12 root straw 0

2017-07-28 15:01:16.240974 7f4dda123760  1 
-4 …

Dealing with some osd timeouts

Certain operations may occasionally take longer for the OSD to process. And the operation may fail, or even make the OSD to suicide. There are many parameters for these timeouts. Some examples :

Thread suicide timed out

heartbeat_map is_healthy 'OSD::osd_op_tp thread 0x7f1ee3ca7700' had suicide timed out after 150
common/HeartbeatMap …