S3QL is a file system that stores all its data online. It supports Amazon S3, Google Storage, and OpenStack and effectively provides you with a hard disk of dynamic, infinite capacity that can be accessed from any computer with Internet access. S3QL provides a standard, full featured Unix file system that is conceptually indistinguishable from any local file system. Additional features include compression, encryption, data de-duplication, immutable trees, and snapshotting, which make it especially suitable for online backup and archiving. The design favors simplicity and elegance over performance and feature-creep. Care has been taken to make the source code as readable and serviceable as possible. Solid error detection, error handling, and extensive automated test cases are provided.
dantalian is a transparent file-tagging system using hard links. Tags (which are directories) can be accessed on the file system level (with or without fuse), allowing maximum interoperability with other applications. Tagging operations are performed with scripts, and can also be hooked into other applications. dantalian is file-agnostic and can be used with any and all types of files. Tags can be organized hierarchically and can also be tagged. With (optional) fuse support, dantalian can also create virtual tags (currently limited to tag intersections (AND), but will be expanded later), which can be accessed transparently on the filesystem level.
RioFS is a userspace filesystem for Amazon S3 buckets that runs on Linux and Mac OS X. It supports versioned and non-versioned buckets in all AWS regions. RioFS is intended as a storage backend for legacy daemons that cannot talk natively to S3. It handles buckets with many thousands of keys and highly concurrent access gracefully.
Gfarm is a distributed filesystem, generally used for large scale cluster computing. It's implemented in userland, and can be mounted by FUSE. It utilizes locality of a file to access a data node, and supports Globus GSI for Wide Area Network. Users can explicitly control file replica location on Gfarm. Gfarm can be used as an alternative storage system to HDFS for Hadoop, Samba, MPI-IO, and GridFTP. Monitoring via ZABBIX and Ganglia is also supported.
bfsync is a file-synchronization tool that allows you to keep a collection of big files synchronized on many machines. It is built around a FuSE filesystem, so repositories can be mounted and the contents can be viewed and modified via the mount point. A collection of commands like commit/push/pull/put/get can be used to control bfsyncs behaviour, and trigger data / history transfers between machines. In addition to synchronizing files between many machines, bfsync can also be used to store backups.