freshmeat: Tired of fscking? Try a journaling filesystem!Feb 18, 2001, 19:30 (5 Talkback[s])
(Other stories by Philipp Tomsich)
"Waiting for a fsck to complete on a server system can tax your patience more than it should. Fortunately, a new breed of filesystem is coming to your Linux machine soon. Journaling filesystems maintain a special file called a log (or journal), the contents of which are not cached. Whenever the filesystem is updated, a record describing the transaction is added to the log. An idle thread processes these transactions, writes data to the filesystem, and flags each processed transaction as completed. If the machine crashes, the background process is run on reboot and simply finishes copying updates from the journal to the filesystem. Incomplete transactions in the journal file are discarded, so the filesystem's internal consistency is guaranteed."
"This cuts the complexity of a filesystem check by a couple of orders of magnitude. A full-blown consistency check is never necessary (in contrast to ext2fs and similar filesystems) and restoring a filesystem after a reboot is a matter of seconds at most."