Book Image

PostgreSQL High Availability Cookbook - Second Edition

By : Shaun Thomas
Book Image

PostgreSQL High Availability Cookbook - Second Edition

By: Shaun Thomas

Overview of this book

Databases are nothing without the data they store. In the event of a failure - catastrophic or otherwise - immediate recovery is essential. By carefully combining multiple servers, it’s even possible to hide the fact a failure occurred at all. From hardware selection to software stacks and horizontal scalability, this book will help you build a versatile PostgreSQL cluster that will survive crashes, resist data corruption, and grow smoothly with customer demand. It all begins with hardware selection for the skeleton of an efficient PostgreSQL database cluster. Then it’s on to preventing downtime as well as troubleshooting some real life problems that administrators commonly face. Next, we add database monitoring to the stack, using collectd, Nagios, and Graphite. And no stack is complete without replication using multiple internal and external tools, including the newly released pglogical extension. Pacemaker or Raft consensus tools are the final piece to grant the cluster the ability to heal itself. We even round off by tackling the complex problem of data scalability. This book exploits many new features introduced in PostgreSQL 9.6 to make the database more efficient and adaptive, and most importantly, keep it running.
Table of Contents (18 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Grouping associated resources

Defining all of the critical resources within Pacemaker is a good start. However, Pacemaker is not concerned with keeping related services operating together. It is designed to facilitate service management for any series of resources over a large array of servers. This is a recurring theme in this chapter, and one we have to overcome to fully leverage Pacemaker's abilities.

One way we can do this is by creating a group of related resources. When we do this, the group represents every member as a whole and must run on one server or another. This prevents the problems we had in the previous recipes, such as the possibility of new resources being started on the wrong node.

We'll create a group in this recipe and discuss other important caveats.

Getting ready

As we're continuing to configure Pacemaker, make sure you've followed all the previous recipes.

How to do it...

Perform these steps on any Pacemaker node as the root user:

  1. Add a group to Pacemaker with crm:
crm configure...