Managing RAID on Linux

ext3 Extensions for the ext2 Filesystem

ext3 is an attempt to add many of the features found in other journaling filesystems to the ext2 filesystem. Many users feel that this design approach will cause ext3 to inherit some problems that have arisen with ext2 over the years, and have instead opted to use a journaling filesystem that has been developed from the ground up, like ReiserFS. However, many also feel that by adding the journaling features onto ext2, users of ext3 are inheriting the time-tested reliability of the ext2 filesystem. And since ext3 is fully forward- and backward-compatible with ext2, users don’t need to go through a tedious backup and restore process to upgrade older ext2 systems.

Regardless of whether you are ready to embrace ext3 or remain a skeptic, two things are certain. First, ext3 will become pervasive, simply because ext2 is so widely deployed. Second, ext2 is always being improved, so just because ext3 inherits its architecture from ext2 doesn’t mean that there isn’t room for it to develop as a filesystem.

ext3 supports journaling for metadata only, as well as combined journaling of data and metadata. That means users can improve the reliability of their filesystems by taking additional safeguards against data loss resulting from a system crash. ext3 inherits filesystem and file size limits from ext2. It also uses the same data structures and organization as ext2.

Support for ext3 has been included with the stable Linux kernel since 2.4.15. Users working ...