Seeding ensures a new cluster will start with an accurate membership count of the number of systems in the cluster. This prevents the possibility of one cluster splitting into multiple subclusters upon initial startup.
A new cluster can be automatically seeded as follows:
When the cluster initially boots, all systems in the cluster are unseeded.
GAB checks the number of systems that have been declared to be members of the cluster in the
The number of systems declared in the cluster is denoted as follows:
/sbin/gabconfig -c -nN
where the variable # is replaced with the number of systems in the cluster.
When GAB on each system detects that the correct number of systems are running, based on the number declared in
/etc/gabtab and input from LLT, it will seed.
If you have I/O fencing enabled in your cluster and if you have set the GAB auto-seeding feature through I/O fencing, GAB automatically seeds the cluster even when some cluster nodes are unavailable.
HAD will start on each seeded system. HAD will only run on a system that has seeded.
HAD can provide the HA functionality only when GAB has seeded.