The Reiser File System (ReiserFS) is a journaling file system that is designed to improve the scalability and performance over the Ext2 and Ext3 file systems. By comparison, ReiserFS provides better disk space utilization, better disk access performance, faster crash recovery, and reliability through data journaling.
ReiserFS uses the POSIX extended access control model.
ReiserFS uses ordered journaling by default. The file system driver collects all data blocks that correspond to one metadata update. These data blocks are written to disk before the metadata is updated. As a result, consistency is achieved for metadata and data without sacrificing performance. The commit policy depends on the journal size but is based on the number of blocks to commit. Using a journal to keep track of recent metadata changes makes a file system check a matter of seconds, even for huge file systems.
ReiserFS provides the best performance and scalability when there are many files and the files are small. It scales and performs extremely well on Linux, out-scaling Ext3 with h-trees. In addition, ReiserFS is designed to very efficiently use disk space. As a result, it is a good choice on Linux where there are many small files in the file system. Because collaboration (email) and many web serving applications have many small files, ReiserFS is best suited for these types of workloads.
For small files, file data and inode information are often stored next to each other. They can be read with a single disk I/O operation, meaning that only one access to disk is required to retrieve all the information needed.