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

Interpreting /proc/meminfo

Administrators familiar with the Linux /proc filesystem know that it is a valuable source for both device status and performance information. The meminfo entry in this directory will always provide copious data regarding the status, contents, and state of the memory in our server.

We care about this as DBAs because file cache and write buffering can drastically affect disk I/O. We are not especially interested in analyzing PostgreSQL's memory usage itself. At the time of writing, current recommendations suggest that PostgreSQL's performance doesn't really improve after shared buffers reach 8 GB. However, for client connections, inode caches, and dirty page flushing, it's more than relevant.

On a modern Linux kernel, there are over 40 different lines of information in /proc/meminfo. Much of this data is not exceptionally useful to a DBA, so this recipe will focus on important fields only.

Getting ready

We will be using the watch and grep commands in this recipe. It...