GAB provides membership and messaging service, both for the cluster as a whole and for groups of applications running it. The GAB membership service provides orderly startup and shutdown of a cluster.
/etc/gabtab is used to configure GAB. Configuration is done with the
gabconfig command. For example, the
-n option of the command specifies the number of nodes in the cluster. GAB is configured automatically when you run the VCS installation script, but you may have to reconfigure GAB when you add a node to a cluster.
gabconfig(1m) manual page.