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 LVM to cluster management

To avoid potential conflicts, we will continue to add resources to Pacemaker in the same order as if we were starting them manually. After DRBD comes our second LVM layer. The primary purpose of Pacemaker in this instance is to activate or deactivate the VG_POSTGRES volume group that we created in the previous chapter.

This is necessary because DRBD cannot demote a primary resource to the secondary status as long as there are any open locks. Any LVM volume group that contains active volumes can cause these kinds of lock. Also, we cannot utilize a volume group that has no active volumes when DRBD is promoted on the second node.

This recipe will explain the steps necessary to manage our VG_POSTGRES/LV_DATA data volume with Pacemaker.

Getting ready

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


Users of some Debian-derivative systems such as Ubuntu need to beware! To avoid potential issues, it may be necessary to...