Initialize a Cluster on the First Host

Log into the initial Proxmox instance, referred to here as host-alpha. Use the cluster management tool to form a new group:

pvecm create alpha-group

This command generates the Corosync authentication material, writes it to /etc/corosync/authkey, and produces an updated /etc/pve/corosync.conf. The cluster services are restarted automatically.

Verify the newly created cluster state:

pvecm status

Sample output:

Cluster information
-------------------
Name:             alpha-group
Config Version:   1
Transport:        knet
Secure auth:      on

Quorum information
------------------
Date:             Tue Jun 25 14:46:32 2024
Quorum provider:  corosync_votequorum
Nodes:            1
Node ID:          0x00000001
Ring ID:          1.5
Quorate:          Yes

Votequorum information
----------------------
Expected votes:   1
Highest expected: 1
Total votes:      1
Quorum:           1  
Flags:            Quorate 

Membership information
----------------------
    Nodeid      Votes Name
0x00000001          1 192.168.103.131 (local)

Add Additional Hosts to the Group

From a second node (host-beta), join the existing cluster by referencing the primary host's address:

pvecm add 192.168.103.131

Enter the root password when prompted. The utility establishes an API session, validates the remote host's certificate fingerprint, and incorporates the node into the quorum. It regenerates configuration files, updates SSH authorizations, and restarts related daemons.

Confirm succesful inclusion:

pvecm status

Example quorum section after two nodes:

Nodes:            2
Expected votes:   2
Total votes:      2
Quorum:           2

Membership information
----------------------
    Nodeid      Votes Name
0x00000001          1 192.168.103.131
0x00000002          1 192.168.103.132

List all members by name:

pvecm nodes

Output:

    Nodeid      Votes Name
         1          1 host-alpha (local)
         2          1 host-beta

Repeat the process for a third member (host-gamma). After inclusion, the node table reflects three active participants:

pvecm nodes

    Nodeid      Votes Name
         1          1 host-alpha (local)
         2          1 host-beta
         3          1 host-gamma

Remove a Member from the Cluster

To detach a node—for example, host-gamma—execute:

pvecm delnode host-gamma

Recheck membership:

pvecm status

Purge residual web interface references:

cd /etc/pve/nodes/
rm -rf host-gamma

Clear Cross-Host Authenticasion Artifacts

Authentication remnants may persist across machines. Remove them from the shared credential store:

cd /etc/pve/priv
# Edit authorized_keys and known_hosts to delete entries for removed hosts