IBM Journaled File System 2 (JFS2)
From Wikipedia, the free encyclopedia
Journaled File System or JFS is a journaling filesystem created by IBM. It is available under the GNU GPL. There are versions for AIX, eComStation, OS/2 and Linux operating systems. HP-UX has another, different filesystem named JFS that is actually an OEM version of Veritas Software's VxFS.
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[edit] History
IBM introduced its Journaled File System (JFS) with the initial release of AIX Version 3.1. This file system, now called JFS1 on AIX, had been the premier file system for AIX over the following decade and had been installed in thousands or millions of customers' AIX systems. Historically, the JFS1 file system is very closely tied to the memory manager of AIX. This design is typical of a closed source operating system, or a file system supporting only one operating system.
In 1995, work began to enhance the file system to be more scalable and to support machines that had more than one processor. Another goal was to have a more portable file system, capable of running on multiple operating systems. The new Journaled File System was first shipped in OS/2 Warp Server for eBusiness in April, 1999, after several years of designing, coding, and testing. It also shipped with OS/2 Warp Client in October, 2000. In December of 1999, a snapshot of the original OS/2 JFS source was granted to the open source community and work was begun to port JFS to Linux.
In June, 2006, JFS version 1.1.11 was released for Linux. Unlike ext3, JFS supports extents, which is a major new feature in ext4.
In parallel to this effort, some of the JFS development team returned to the AIX Operating System Development Group in 1997 and started to move this new JFS source base to the AIX operating system. In May, 2001, a second journaled file system, Enhanced Journaled File System (JFS2), was made available for AIX 5L.
[edit] JFS in Linux
| Distribution | Initial version | Release Date |
|---|---|---|
| Arch Linux | 0.6 | 03/2004 |
| Ark Linux | 1.0 alpha 6 | 01/2003 |
| Debian GNU/Linux | 3.0 | 07/2002 |
| Gentoo Linux | 1.4 | - |
| Knoppix Linux | 3.1 | - |
| Mandriva Linux (formerly Madrake Linux) | 8.0 | 2001 |
| Fedora (formerly Red Hat Linux) | 7.3 | 05/2002 |
| Slackware | 8.1 | 06/2002 |
| SuSE Linux | 7.3 | 2001 |
| Turbolinux | 7.0 | - |
| United Linux | 1.0 | - |
| Ubuntu | 4.10 | 10/2004 |
| Kate OS | 1.01 | - |
All distributions which are derivatives of those mentioned above should normally have JFS support, unless it's specifically removed due to space restrictions or other concerns.
JFS is not officially supported by several distributions, including Suse and Fedora. The April 2006 edition of Linux Magazine even went as far as saying that because of this, "JFS, a filesystem developed by IBM, failed to establish a foothold in the industry" (page 31). In the same paragraph, XFS is hailed, though it is often not officially supported either.
According to reviews and benchmarks of the available filesystems for Linux, JFS is fast and reliable, with consistently good performance under different kinds of load, contrary to other filesystems that seem to perform better under particular usage patterns, for instance with small or large files. Another characteristic often mentioned, is that it's light and efficient with available system resources and even heavy disk activity is realised with low CPU usage.
