The ReiserFS is a general-purpose computer file system designed and implemented by a team led by Hans Reiser. It is currently supported by Linux and may be included in other operating systems in the future. With Linux version 2.4.1, it was the first journaling file system to be included in the standard kernel.
The most-publicised advantage over the stock Linux file system, EXT2, is that it is a journalled file system which uses journalled metadata. This feature greatly reduces the risk of filesystem corruption (and the need for lengthy file system checks) after an unscheduled system shutdown through power outage or a system crash. Unfortunately, converting a system to ReiserFS requires users of EXT2 to completely reformat their disks, which is a disadvantage not shared by its main competitor EXT3.
ReiserFS also handles directories containing huge numbers of small files very efficiently. This is important when handling Usenet news spools.