A common interpretation of a functional server is one that runs on its own recognizance. After being rebooted, it starts all necessary services and does its job as configured. It might be hard to believe, but we want to fight that inclination for two important reasons:
- Pacemaker is a state machine
- Pacemaker needs total control of any service it manages
Pacemaker wants to start services itself so it knows that the current status is the one it created. It will perform tests to obtain this information, but for things such as DRBD, this isn't always reliable. It's generally safer to start from scratch. Beyond this, if a service that isn't supposed to be running starts, Pacemaker will only have to stop it anyway.
In this recipe, we'll quickly cover which services to disable on each of our PostgreSQL nodes.
As we're continuing to configure Corosync and Pacemaker, make sure you've followed all the previous recipes.