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

Configuring Corosync

Once Corosync and Pacemaker are installed, we only need to modify a single configuration file to activate them. As we've mentioned earlier and shown in the introduction diagram, Corosync is the conduit that Pacemaker uses for communication. Corosync also binds itself to services that rely on its channels, so it will also launch Pacemaker on our behalf.

This recipe will explain how to create a simple configuration for Corosync that will establish a secure Pacemaker cluster.

Getting ready

We have already installed everything we need, but if we are running an older Debian-based system such as Ubuntu or Mint, we have one more step. Before Corosync will work properly, we need to enable its startup script. Open the /etc/default/corosync file and make sure it contains this line:


Without it, Corosync won't run even if we start it manually. We removed it from system boot time, but that doesn't mean we never want it to run at all!

How to do it...

For this recipe, we...