Summary:
As Linux made its way further into the enterprise, a key feature that it was lacking at one point in time was a journaling file system. This was true in 1999, but today there are four journaling file systems that can solve enterprise server requirements. This article focuses on one of them: JFS.

As Linux made its way further into the enterprise, a key feature that it was lacking at one point in time was a journaling file system. This was true in 1999, but today there are four journaling file systems that can solve enterprise server requirements. This article focuses on one of them: JFS.

The file system is one of the most important parts of an operating system. It stores and manages user data on disk drives and ensures that what's read from storage is identical to what was originally written. In addition to storing user data in files, the file system also creates and manages information about files and about itself. Besides guaranteeing the integrity of all that data, file systems are also expected to be extremely reliable and have excellent performance.

Before the year 2000, Ext2 was the de facto file system for most Linux machines; it was robust, reliable, and suitable for most deployments. However, as Linux displaced Unix and other operating systems in more and more large server and computing environments, Ext2 was pushed to its limits. In fact, many now-common requirements - large hard-disk volumes, quick recovery from crashes, high-performance I/O, and the need to store millions of files representing terabytes of data - exceed the capabilities of Ext2.

Fortunately, a number of other Linux file systems pick up where Ext2 leaves off. Indeed, Linux now offers four alternatives to Ext2: Ext3, JFS, ReiserFS, and XFS. In addition to meeting some or all of the previously mentioned requirements, each of these alternative file systems also supports journaling, a feature certainly demanded by enterprises but beneficial to anyone running Linux. A journaling file system can simplify restarts, reduce fragmentation, and accelerate I/O. Better yet, journaling file systems make fscks a thing of the past.