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 block-level replication

DRBD is the next component of our software stack. Unlike LVM, it requires at least two servers to function normally. One server acts as the data Primary, and the other acts as a Secondary. These roles can be switched at any time, depending on which server is running PostgreSQL.

For now, we are going to focus on configuring and activating DRBD as part of our stack.

Getting ready

By now, we hope you've followed the recipe in Getting starting with the Linux Volume Manager on two servers with /dev/sdb as physically identical storage on each server. While DRBD can operate in standalone mode on a single server, this is actually more advanced usage. The steps in this recipe are best applied identically on both of the servers simultaneously, unless noted otherwise.

How to do it...

For the purposes of this recipe, we will assume that the /dev/VG_DRBD/LV_DATA device already exists. The two PostgreSQL nodes for this example are named pg1 and pg2 and are located on the 192...