Linear Tape File System

Linear Tape File System (LTFS) allows files stored on magnetic tape to be accessed in a similar fashion to those on disk or removable flash drives. It requires both a specific format of data on the tape media and software to provide a file system interface to the data.

The technology, based around a self-describing tape format developed by IBM, was adopted by the LTO Consortium in 2010.

Magnetic tape data storage has been used for over 50 years, but typically did not hold file metadata in a form easy to access or modify independent of the file content data. Often external databases were used to maintain file metadata (file names, timestamps, directory hierarchy) to hold this data but these external databases were generally not designed for interoperability and tapes might or might not contain an index of their content. In Unix-like systems, there is the tar interoperable standard, but this is not well-suited to allow modification of file metadata independent of modifying file content data - and does not maintain a central index of files nor provide a filesystem interface or characteristics.

LTFS technology was first implemented by IBM as a prototype running on Linux and Mac OS X during 2008/2009. This prototype was demonstrated at NAB 2009. Based on feedback from this initial demonstration and experience within IBM the filesystem was overhauled in preparation for release as a product. The LTFS development team worked with the vendors of LTO tape products (HP and Quantum) to build support and understanding of the LTFS format and filesystem implementation leading up to the public release.

The LTFS Format Specification and filesystem implementation were released on April 12, 2010 with the support of IBM, HP, Quantum, and the LTO Consortium.

LTFS v2.0.0 was released in March 2011, improving the text to clarify and remove ambiguity. It also added support for sparse files; persistent file identifiers; virtual extended attributes for filesystem metadata and control - and defined minimum and recommended blocksize values for LTFS volumes, for compatibility across various HBA hardware implementations.

Version 2.0.0 defines rules for how the version number may change in future, and how compatibility is maintained across varying implementations. All implementations must: