The inventory must define these hosts to run:

• cluster_machines: Set of hosts in the cluster
• hypervisors: Set of hosts to launch virtual machines
• standalone_machine: To define only the cluster is composed with one host (replace cluster_machines)

Prerequisite

This step is useful only for the installed hosts by a debian installer build with build_debian_iso.

...

• clients: Set of hosts that must be ceph-client

• mons: Set of hosts to that must be ceph-mon

• osds: Set of hosts to that must be ceph-osd

The roles are explained in the documentation here.

The inventory must define these variables to run the step:

• ceph_osd_disk: Device to use as OSD stock datas (only for ceph-osd hosts)

• osd_pool_default_min_size: Minimal number of available hosts in the clusterOSD to ensure cluster success

• osd_pool_default_size: Number of hosts OSD in the cluster

Ceph provides ansible rules to configure the software, you can read the documentation here.

High availability (via corosync and pacemaker)