Reiser4 is computer file system, a new version of the ReiserFS file system, written from scratch. It has following advanced features:
- efficient support of small files,
- handling of large and very large directories with hundreds of millions of files,
- flexible plugin infrastructure,
- atomic file system modification,
- efficient journalling through wandering logs,
- dynamically optimized disk-layout (through allocate-on-flush, and online repacker), and
- the integration of meta-data into the file system name-space.