The linux implementation of a log-structured file system

Toward enhancing the reliability of the Linux file system, we are developing a new log-structured file system (NILFS) for the Linux operating system. Instead of overwriting existing blocks, NILFS appends consistent sets of modified or newly created blocks continuously into segmented disk regions. This writing method allows NILFS to achieve faster recovery time and higher write performance. The address of the block that is written to changes for each write, which makes it difficult to apply modern file system technologies such as B-tree structures. To permit such writing on the Linux kernel basis, NILFS has its own write mechanism that handles data and meta data as one unit and allows them to be relocated. This paper presents the design and implementation of NILFS focussing on the write mechanism.