High Availability (HA) is not just an industry term. The fact that something needs to be available usually also means that it is super important, and that the service must be available to clients, no matter the cost.
High Availability is important in the PostgreSQL world. A database is the central component of most setups, and therefore, availability of the service is the key.
In this chapter, the following topics will be covered:
Understanding the purpose of High Availability
Measuring availability
Linux-HA (Heartbeat), STONITH, and Pacemaker
Terminology and concepts
PostgreSQL and High Availability