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

Adding a virtual IP to hide the cluster

We discussed virtual IP addresses earlier; now, it's time to leverage them properly. A virtual IP is not a service in the traditional sense, but it does provide functionality that we need in a highly-available configuration. In cases where we also have control over DNS resolution, we can even assign a name to the virtual IP address to insulate applications from future changes.

For now, this recipe will limit itself to outlining the steps required to add a transitory IP address to Pacemaker.

Getting ready

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

How to do it...

We will assume that the IP address exists as a predefined target for our PostgreSQL cluster. Users and applications will connect to it instead of the actual addresses of pg1 or pg2.

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

  1. Add an IP address primitive to Pacemaker with crm:
crm configure primitive pg_vip ocf:heartbeat...