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

Mitigating the impact of hardware failure

Software can have bugs, and PostgreSQL is no exception. Bugs in the database software rarely, if ever, lead directly to data corruption. Hardware can fail too, but hardware problems are not always so straightforward.

Disk, CPU, or memory failures don't always cause the server to crash. In fact, these failures can persist for weeks or even months before their detection by a monitoring infrastructure. Disk failures are generally abstracted away by RAID or SAN devices, and these arrays are designed to readily handle online rebuilds. Other types of failures are more subtle.

CPU or memory problems can manifest in several different ways. In order for PostgreSQL to function, the data from disk must be read into memory to be processed by the CPU. During any of these transition states, a bad CPU or RAM module can inject an invalid checksum or data value inconsistent with the rest of the database. However, PostgreSQL generally assumes that the database is consistent...