Fixing GlusterFS not in 'Peer in Cluster' State Error

When creating a Glusterfs deployment, after peering your other nodes:

gluster peer probe node1

you can see the status of the cluster using gluster peer status, where you might see something like this:

Hostname: 192.168.0.122
Uuid: 35c563b6-b54a-4fb6-98a9-243d34e0a82e
State: Accepted peer request (Connected)

but in this State, you cannot create a volume yet, and you might get an error like:

ubuntu@61d8372c31e8:~$ sudo gluster volume create replicated-data replica 3 192.168.0.121:/gluster/02 192.168.0.122:/gluster/02 192.168.0.123:/gluster/02
volume create: replicated-data: failed: Host 192.168.0.122 is not in 'Peer in Cluster' state

If it is stuck in this state, using the UUID from the peer status above, you can modify the /var/lib/glusterd/peers/{UUID} file, where you'll see a state=4 line.

Update this line to read state=3 on, both, this node, and the UUID for the first node as well on the peer node if needed, then restart glusterd:

systemctl restart glusterd

and recheck the peer status:

Hostname: 192.168.0.122
Uuid: 35c563b6-b54a-4fb6-98a9-243d34e0a82e
State: Peer in Cluster (Connected)

at which point you can proceed to create a volume.