Moose File System (MooseFS / MFS) is a fault tolerant, network distributed file system. It spreads data over several physical servers, which are visible to the user as one resource. For standard file operations MooseFS mounted with FUSE acts like other Unix-alike file systems: it has a hierarchical structure; it stores POSIX file attributes; and it supports special files, symbolic links, and hard links. Access to the file system can be limited based on IP address and/or password. It offers high reliability, since several copies of the data can be stored across separate computers. Capacity is dynamically expandable by attaching new computers or disks. Deleted files are retained for a configurable period of time (with a file system level "trash bin"). MooseFS supports coherent snapshots of files, even while the file is being written or accessed.
fsprotect is a set of scripts that combine tmpfs and aufs to make existing filesystems immutable. After the filesystems are protected, everything that is written will be lost when the computer powers off. It is a great tool for testing and for public computers like those in schools, libraries, etc. It is also very easy to use. It is currently available only for Debian-based systems.
Hgfs is a read-only filesystem interface to Mercurial repositories. The interface gives access to the commit message, manifest, and files of each revision, and to .tgz's of each revision (the .tgz's are generated as they are read). The filesystem is a front-end for the Mercurial library that comes with it. All code is written in Limbo, for Inferno.
Lessfs is a high performance inline data deduplicating file system for Linux. Lessfs complies to the POSIX standard and is very useful for backup purposes as well as providing storage for virtual machine images. Although lessfs is a file system that is implemented in user space with FUSE, it offers decent performance. Lessfs is capable of handling data rates up to 350MB/sec. It supports filesystem encryption.
FSter is a virtual filesystem implementation based on FUSE and exploiting Tracker's indexer to allow access to files according to the metadata with which they’re associated. Its behavior is highly customizable with XML configuration to describe in detail the desired hierarchy of files.