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 Nagios to monitor a database host

Once Nagios is installed, it will automatically configure a few basic monitors directed toward its own server. If we click on the Hosts link in the web administration site, we are presented with this:

The local server is all that we are currently watching. This is useful to verify that Nagios is working as intended, but we need to monitor one or more database servers as well. In this recipe, we will learn how to watch external servers. By the end, we should see at least one more server listed by Nagios.

Getting ready

Initially, Nagios can only monitor remote servers by checking exposed services such as HTTP, FTP, or PostgreSQL. To check items such as CPU, RAM, or disk space, we need to rely on Nagios Remote Plugin Executor (NRPE) to forward system information to the monitoring server upon request. This means that NRPE must be installed on any server we want to monitor, including our PostgreSQL servers.

To install this on Debian-based servers, use...