One of several reasons for the greatness of Ceph is that almost all the operations on a Ceph cluster can be performed online, which means that your Ceph cluster is in production and serving clients, and you can perform administrative tasks on the cluster without downtime. One of these operations is upgrading the Ceph cluster version.
Since the first chapter, we have been using the Giant release of Ceph, which was intentional so that we could demonstrate upgrading the Ceph cluster version from Giant to Hammer. As per best practice, you should follow the recommended upgrade sequence for Ceph, which is in the following order:
The ceph-deploy tool
The Ceph monitor daemons
The Ceph OSD daemons
The Ceph metadata servers
The Ceph Object Gateways
As a general rule, it's recommended that you upgrade all the daemons of a specific type (for example, all ceph-mon
daemons, all ceph-osd
daemons, and so on) to ensure that they are all on the same release.