Before you can write data to a PG, it must be in an ``active`` state and it
will preferably be in a ``clean`` state. For Ceph to determine the current
state of a PG, peering must take place. That is, the primary OSD of the PG
-(that is, the first OSD in the Acting Set) must peer with the secondary and
+(the first OSD in the Acting Set) must peer with the secondary and the following
OSDs so that consensus on the current state of the PG can be established. In
the following diagram, we assume a pool with three replicas of the PG: