Log-structured filesystem

A log-structured filesystem is a generalization of a journaling filesystem. In a log-structured filesystem, rather than being a conventional filesystem with an added journal log, the journal log itself is used as the fundamental basis for the filesystem, meaning that both filesystem meta-data and the filesystem data are journaled.

Such filesystems allow for accessing old versions of files (aka time-travel, snapshots) whereas journaling filesystems may lose or corrupt file content due to disk errors. Both types don't require long consistency checks on reboot because only the journal needs to be reviewed on startup, instead of the entire disk (as in UFS, FFS, ext2, etc.)

External links

• M. Rosenblum and J. Ousterhout. The design and implementation of a log-structured file system. Proceedings of the 13th Symposium on Operating System Principles, pages 1-15, October 1991.