Introduction

Linux provides several utilities for each type of file system for looking at file system metadata and analyzing on-disk structures. With these tools, you can view a file system's structures. Generally, these tools are intended for use by developers of a file system to analyze structures; however, they can also be used to find performance problems.

In this case study, we'll provide examples of viewing an inode on Ext2, JFS, ReiserFS, and XFS file systems. Next, we'll show how to tune each type of file system by using an external log. An external log improves performance because the log updates are saved to a different partition than the corresponding file system. This reduces the number of hard disk seeks. We'll show the results of using file system test programs on a file system that uses an external log. We'll also discuss mount options that some file systems have to increase file system performance. We'll then show how you can identify bottlenecks on physical disks by using the sar and iostat tools.