This is the journaling version (called ext3) of the second extended file system, the de facto standard Linux file system for hard disks.

The journaling code included in this driver means you do not have to run fsck (file system checker) on your file systems after a crash. The journal keeps track of any changes that were being made at the time the system crashed, and can ensure that your file system is consistent without the need for a lengthy check.

Other than adding the journal to the file system, the on-disk format of ext3 is identical to ext2. It is possible to freely switch between using the ext3 driver and the ext2 driver, as long as the file system has been cleanly unmounted, or fsck is run on the file system before the switch.

To add a journal on an existing ext2 file system or change the behavior of ext3 file systems, you can use the tune2fs utility. To modify attributes of files and directories on ext3 file systems, use chattr. You need e2fsprogs version 1.20 or later in order to create ext3 journals (available at http://sourceforge.net/projects/e2fsprogs).