Setting up a simple HA cluster

We will now go through setting up a simple database cluster. For this setup, we will need two database nodes, one extra node for providing quorum, and a cluster IP that will be assigned to the node that is running as the primary. Each database node will store the database on a local filesystem.

Preparing the servers

Install the operating system as you would normally. You should prefer fresher Linux distributions because Linux-HA support has really matured in distributions such as Red Hat Enterprise Linux 7 and its derivatives.

For the network setup, it is really important that the hostnames are set properly before you start setting up High Availability. Pacemaker uses hostnames to identify systems, and that makes changing a node's hostname a rather painful procedure. Make sure that the hostname lookup works properly on all nodes, either by using a DNS server or by adding entries to /etc/hosts on all the nodes. Set reasonably short hostnames and avoid including...