3 Requirements #

All machines (cluster nodes and arbitrators) that will be part of the Geo cluster have the following software installed:

The virtual IPs to be used for each cluster site must be accessible across the Geo cluster.

The sites must be reachable on one UDP and TCP port per booth instance. That means any firewalls or IPsec tunnels in between must be configured accordingly.

Other setup decisions may require to open more ports (for example, for DRBD or database replication).

All cluster nodes on all sites should synchronize to an NTP server outside the cluster. For more information, see the Administration Guide for SUSE Linux Enterprise Server 12 SP4, available at http://www.suse.com/documentation/. Refer to the chapter Time Synchronization with NTP.

If nodes are not synchronized, log files and cluster reports are very hard to analyze.

Use an uneven number of members in your Geo cluster. In case the network connection breaks down, this makes sure that there still is a majority of sites (to avoid a split brain scenario). In case you have an even number of cluster sites, use an arbitrator.

The cluster on each site has a meaningful name, for example: amsterdam and berlin.

The cluster names for each site are defined in the respective /etc/corosync/corosync.conf files:

totem {
    [...]
    cluster_name: amsterdam
    }

This can either be done manually (by editing /etc/corosync/corosync.conf) or with the YaST cluster module (by switching to the Communication Channels category and defining a Cluster Name). Afterward, stop and start the pacemaker service for the changes to take effect:

# systemctl stop pacemaker
# systemctl start pacemaker