I am working through a Ceph course right now (ceph learning path from packtpub). The course is ok, but has a lot of errors, and isn't always the most accurate. The course expects that you use ceph-ansible to do a lot of the work. You start by creating a 3 node cluster.
So, the starting value of
[mons] ceph-node1 ceph-node2 ceph-node3 [osds] ceph-node1 ceph-node2 ceph-node3 [clients] client-node1
Now, the current section has you create a second 3-node cluster to serve as a remote backup.
To do this, the course has you modify the
/etc/ansible/hosts file to the following:
#Primary site (ceph-node1): [mons] ceph-node1 ceph-node2 ceph-node3 [osds] ceph-node1 ceph-node2 ceph-node3 [clients] client-node1 #Secondary site (ceph-node5): [mons] ceph-node5 ceph-node6 ceph-node7 [osds] ceph-node5 ceph-node6 ceph-node7
The installation of ceph-ansible is done via ceph-node5 with a different all.yml file, indicating a different cluster name. What I am trying to understand is how this would indicate to ceph-ansible that there are two separate clusters. If the /etc/ansible/hosts file is in .ini format, which ansible hostfiles are, any lines that begin with a # should be parsed as comments.
So, does ceph-node5 see the other installations on nodes 1,2,3 and ignore them as a separate cluster? After all, ceph-node5 has it's own
all.yml with instruction that the hosts should be part of the backup cluster. Will it try to add 1,2,3 as nodes?
The text I am working with is really sparse on details, and trying to dig into the ceph-ansible github page hasn't been especially helpful.
I'm just trying to understand the mechanics of how this works. Any help would be appreciated, thank you!