One question regarding Ceph that comes up frequently is: Where do you change ceph.conf file? On admin node? On each node manually? Or will it magically replicate on it’s own?
The answer is that you change the the ceph.conf only in one place. You change it on the admin node and use ceph-deploy to deploy the changes on all other nodes
For example: if you have a cluster consisting of n0, n1 and n2, you would do it like this
#login to admin node cd my-cluster ceph-deploy --overwrite-conf admin n0 n1 n2