[ClusterLabs] Adding a node to the cluster deployed with "Unicast configuration"

[Ken Gaillot]

On 02/22/2017 08:44 AM, Alejandro Comisario wrote:
> Hi everyone, i have a problem when scaling a corosync/pacemaker
> cluster deployed using unicast.
> 
> eg on corosync.conf.
> 
> nodelist {
> node {
> ring0_addr: 10.10.0.10
> nodeid: 1
> }
> node {
> ring0_addr: 10.10.0.11
> nodeid: 2
> }
> }
> 
> Tried to add the new node with the new config (meaning, adding the new
> node) nad leaving the other two with the same config and started
> services on the third node, but doesnt seem to work until i update the
> config on the server #1 and #2 and restart corosync/pacemaker which
> does the obvious of bringing every resource down.
> 
> There should be a way to "hot add" a new node to the cluster, but i
> dont seem to find one.
> what is the best way to add a node without bothering the rest ? or
> better said, what is the right way to do it ?
> 
> PS: i can't implement multicast on my network.

AFAIK, in this situation, there's no way to avoid restarting corosync
(and thus pacemaker, too). But, you can put your cluster into
maintenance mode beforehand, so pacemaker will leave all your services
running, and re-detect them once it starts again. Once the cluster
status looks good again, you can leave maintenance mode.