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

Viewing past performance with sar

While there are many tools to view or analyze the current server performance and behavior, how do we examine historical activity? Most Linux systems rotate logfiles in /var/log for varying periods of time. Unfortunately, these are programs and system logs, not performance measurements.

When we installed the sysstat package in a previous recipe, we gained the use of the sar utility. Some argue that sar is the Swiss Army knife of metric collection. A simple invocation can display past data regarding memory, CPUs, IRQs, disk devices, networks, or even TTYs.

When administering a highly-available server, there are few things as helpful as performance trends. Let's examine them.

Getting ready

As sar and iostat are both part of the sysstat package, we recommend that you review the Evaluating current disk performance with iostat recipe before continuing.

How to do it...

Collect some sample sar data by following these steps:

  1. Display the default sar output with the following...