ReiserFS is a journaling file system that is free if your OS is free, and comes at a licensing cost if your OS is not free. It has excellent performance on large directories and small files, using "dancing trees" instead of B-trees, and does meta-data journaling to improve file-system stability across system crashes.
Unlike "classic" filesystems, Reiser allows you to have files that occupy less than one sector on the disk (i.e. it can store several tiny files or tails of files on the same sector) through its tree organization.
As of version 3.6, ReiserFS supports:
- A maximum of 232 - 3 files in total
- A maximum of 232 - 4 files in a single directory (In practice this value is limited by the hash function. The r5 hash allows about 1 200 000 file names without collisions.)
- A theoretical maximum file size of 1 EiB (260) but the page cache limits this to 16 TiB on architectures with 32 bit integers.
- A maximum of 232 number links to a file
- and A maximum filesystem size of 16 TiB (232) using 4KiB blocks
- http://www.namesys.com - the ReiserFS homepage
- http://p-nand-q.com/download/rfstool/reiserfs_docs.html - Documentation regarding the format of ReiserFS