The {PVE} cluster manager `pvecm` is a tool to create a group of
physical servers. Such a group is called a *cluster*. We use the
http://www.corosync.org[Corosync Cluster Engine] for reliable group
-communication, and such clusters can consist of up to 32 physical nodes
-(probably more, dependent on network latency).
+communication. There's no explicit limit for the number of nodes in a cluster.
+In practice, the actual possible node count may be limited by the host and
+network performance. Currently (2021) there are reports of clusters (using
+high-end enterprise hardware) with over 50 nodes in production.
`pvecm` can be used to create a new cluster, join nodes to a cluster,
leave the cluster, get status information and do various other cluster
Role of SSH in {PVE} Clusters
-----------------------------
-{PVE} utilizes SSH tunnels for various operations.
+{PVE} utilizes SSH tunnels for various features.
-* Proxying terminal sessions of node and containers between nodes
+* Proxying console/shell sessions (node and guests)
+
-When you connect another nodes shell through the web interface, for example, a
-non-interactive SSH tunnel is started in order to forward the necessary ports
-for the VNC connection.
+When using the shell for node B while being connected to node A, connects to a
+terminal proxy on node A, which is in turn connected to the login shell on node
+B via a non-interactive SSH tunnel.
-* VM and CT memory and local-storage migration, if the cluster wide migration
- settings are not configured 'insecure' mode. During a VM migration an SSH
- tunnel is established between the target and source nodes.
+* VM and CT memory and local-storage migration in 'secure' mode.
++
+During the migration one or more SSH tunnel(s) are established between the
+source and target nodes, in order to exchange migration information and
+transfer memory and disk contents.
* Storage replication
projects / pve-docs.git / blobdiff