Book Image

PostgreSQL 9 High Availability Cookbook

By : Shaun Thomas
Book Image

PostgreSQL 9 High Availability Cookbook

By: Shaun Thomas

Overview of this book

A comprehensive series of dependable recipes to design, build, and implement a PostgreSQL server architecture free of common pitfalls that can operate for years to come. Each chapter is packed with instructions and examples to simplify even highly complex database operations. If you are a PostgreSQL DBA working on Linux systems who want a database that never gives up, this book is for you. If you've ever experienced a database outage, restored from a backup, spent hours trying to repair a malfunctioning cluster, or simply want to guarantee system stability, this book is definitely for you.
Table of Contents (12 chapters)
11
Index

Maintaining an XFS filesystem

Conventional wisdom regarding Linux filesystems suggests that file defragmentation is not a necessary task. While this is true in general, file fragmentation isn't something we should allow to spiral out of control. PostgreSQL storage files are limited to 1 GB in size, yet we configured XFS to preallocate no more than 1 MB at a time.

This introduces the potential for data fragmentation on OLTP systems or any database cluster where several tables experience high turnover. To prevent this from adversely affecting sequential scans, and to promote good filesystem health in general, we need to track and potentially correct overly fragmented files.

XFS provides two tools suited to this activity. The first is xfs_db, which provides information about an XFS filesystem. The second is xfs_fsr, which allows us to defragment XFS while it is still mounted and active. This recipe will cover the basic usage of these tools to keep our high availability server performing...