31 Mar
2021
31 Mar
'21
2:52 p.m.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Wednesday, March 31, 2021 9:01 AM, Stefan Kooman <stefan(a)bit.nl> wrote:
For best performance you want to give the MONs their
own disk,
preferably flash. Ceph MONs start to use disk space when the cluster is
in an unhealthy state (as to keep track of all PG changes). So it
depends as well. If you know you can fix any kind of disk / hardware
problem within a certain time frame, you don't need that big drives.
But if the MONs run out of disk space it's a show stopper.
You might run into deadlocks when trying to use CephFS on the MDS
nodes themselves, so try to avoid that.
Thanks Stefan for your answer.
That totally makes sense, so on my nodes 1, 2 and 3 which will have MON+MGR+MDS I will add
an additional SSD disk just for MON.
Now because I am planning to use cephadm which deploys everything in containers what would
be the best point point in order to mount that dedidcated SSD disk? Would you suggest to
simply mount that disk under /var/lib/docker or even /var/lib/docker/volumes and like that
have all the containers (MGR+MDS+MON) use the dedicated disk? or is there a ceph.conf
config parameter where I can say which disk I want to use for MON? or any other best
practice suggestions in this regard?