Linear Tape File System (LTFS) refers to both the format of data recorded on magnetic tape media and the implementation of specific software that uses this data format to provide a file system interface to data stored on magnetic tape. The Linear Tape File System format is a self-describing tape format developed by IBM to address tape archive requirements. The LTFS Format specification, which was adopted by the LTO Technology Provider Companies, defines the organization of data and metadata on tape - files stored in hierarchical directory structure. Data tapes written in the LTFS Format can be used independently of any external database or storage system allowing direct access to file content data and file metadata. This format makes it possible to implement software that presents a standard file system view of the data stored in the tape media. This file system view makes accessing files stored on the LTFS formatted media similar to accessing files stored on other forms of storage media such as disk or removable flash drives.
The Linear Tape File System format is an open description of the layout of data-structures stored on a sequential-access media. These data-structures hold the file content data and associated file metadata. Data media, such as LTO data tape, written using this format can be exchanged between systems that understand the Linear Tape File System format. Software systems that understand the format can provide users with a file system view of the media. Software systems may alternatively understand the format only to the degree that allows the system to read data from the media, or produce a tape that can be accepted by other systems that implement the Linear Tape File System format.
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The Linear Tape File System format was announced on April 12, 2010, and presented at the National Association of Broadcasters (NAB) trade show.[1] This announcement was made in conjunction with announcing the public availability of the IBM Long Term File System software product that uses the LTFS Format.
Magnetic tape data storage has been used for over 50 years. Prior to the introduction of the Linear Tape File System format, tapes used in open systems typically did not hold file metadata in a form that is easy to access or modify independent of the file content data. Instead, the tapes often contained files stored in a trivial sequence, without any directories or even filenames. Various external databases were used to maintain file metadata (file names, timestamps, directory hierarchy) to hold this data independent of the tape media.
For example, both backup software and hierarchical storage management (HSM) software typically maintain a database separate from the tape media. This type of software often allows indexing and accessing data spread over entire tape libraries, but these external databases are generally not designed for interoperability. Tapes in the system may or may not contain an index of their content. The index format depends on the software used to write the tape and is generally not interoperable with other systems.
In Unix-like systems, the tar format is an interoperable standard designed to allow encapsulation of multiple files for tape storage. Tar includes the files content and file-based metadata in a per-file header structure but does not maintain a central index of files. Tar allows one to create self-describing tapes, but does not provide a filesystem interface or characteristics. The tar format is not well-suited to allow modification of file metadata independent of modifying file content data.
The 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 and enjoyed the support of IBM, HP, Quantum, and the LTO Consortium.
The early versions of LTFS released in 2010 were based on the on-media format described in the "LTFS Format Specification v1.0" document. In March 2011 IBM released an updated document "LTFS Format Specification v2.0.0". The updated specification improved the text to remove ambiguity and clarify the intent of the specification. Additionally, the updated specification extends the LTFS Format to:
Version 2.0.0 of the LTFS Format Specification defines rules for how the Format Specification version number may change in future and how compatibility is maintained across varying implementations of the specification. In particular, all implementations compliant with version 2.0.0 (and later versions) must correctly read media that was compliant with any prior versions of the LTFS Format Specification. All implementations compliant with version 2.0.0 (and later versions) must write media that is compliant with the "current" version of the LTFS Format Specification. Where the "current" version is the version of the LTFS Format Specification with which the implementation claims compliance. This specifically means that media modified by an implementation compliant with version 2.0.0 of the format specification will implicitly update the media to be compliant with LTFS Format Specification version 2.0.0. (This update only impacts the LTFS Index written to the media by the updated implementation.)
Implementations in compliance with version 2.0.0 (and later versions) of the LTFS Format Specification will correctly read all media generated using prior versions of the LTFS Format Specification.
Support for the LTFS Format Specification version 2.0.0 is included in the open-source implementation of the Linear Tape File System version 1.2.0.
| Format Specification Version | Specification Published | Conforming Software |
|---|---|---|
| LTFS Format Specification v1.0 | April 2010 | IBM Long Term File System (LTFS) v1.0.0, v1.0.1 HP Linear Tape File System (LTFS) v1.0.0, v1.1.0 |
| LTFS Format Specification v2.0.0 | March 2011 | IBM Linear Tape File System - Single Drive Edition (LTFS-SDE) v1.2.0 |
| Developer(s) | IBM |
|---|---|
| Initial release | April 2010 |
| Stable release | 1.2.2 / March 28, 2011 |
| Development status | Active |
| Written in | C |
| Operating system | Linux, Mac OS X, Microsoft Windows |
| Platform | x64, Intel x86 - 32-bit |
| Available in | English |
| Type | Storage software |
| License | GNU Lesser General Public License |
| Website | ibm.com/systems/storage/tape/ltfs/ |
The IBM Linear Tape File System - Single Drive Edition product is software developed by IBM to implement a tape-based file system using the Linear Tape File System Format. This software implements the LTFS Format and allows tapes to be formatted as an LTFS Volume. These LTFS Volumes may then be mounted using the Linear Tape File System software allowing users and applications direct access to files and directories stored on the tape, including drag-and-drop of files.
Using the Linear Tape File System, files can be created on tape and accessed similar to the process of creating and accessing files on an external hard drive or a USB flash drive. Applications, such as file browsers, image viewers and media players can directly browse and access files on tape. LTFS enables easy and simple use of tapes in desktop computers and embedded systems.
IBM released the first version of the Linear Tape File System product as open source software. This release supports the Linear Tape Open Ultrium 5 (LTO-5) drives. Every release of IBM LTFS - SDE is based on the Linear Tape File System Format Specification developed by IBM and released as an open specification.
Prior to version 1.2.0 the "IBM Linear Tape File System - Single Drive Edition" product was distributed under the product name "IBM Long Term File System".
| Developer(s) | IBM |
|---|---|
| Initial release | June 2011 |
| Stable release | 2.0.0 / March 28, 2011 |
| Development status | Active |
| Written in | C |
| Operating system | Linux |
| Platform | x64, Intel x86 - 32-bit |
| Available in | English |
| Type | Storage software |
| License | Proprietary commercial software |
| Website | ibm.com/systems/storage/tape/ltfs/ |
The IBM Linear Tape File System - Library Edition (LTFS-LE) product is software developed by IBM to implement a tape-based file system using the Linear Tape File System Format. This software implements the LTFS Format and allows tapes to be formatted as an LTFS Volume. These LTFS Volumes may be used in a tape library along with the LTFS-LE software. The LTFS-LE software allows the user to mount the tape library allowing users and applications direct access to all files and directories stored in the LTFS Volumes. When the library is mounted each LTFS-formatted tape cartridge in the library appears as a separate folder under the filesystem mount point. The user or application can navigate into each of these folders to access the files stored on each tape. The LTFS-LE software automatically controls the tape library robotics to load and unload the necessary LTFS Volumes to provide access to the stored files.
IBM Linear Tape File System - Library Edition implements the LTFS Format Specification version 2.0.0. LTFS Volumes produced in LTFS-LE are fully compatible with the open-source LTFS-SDE software product. LTFS-LE is available for all current IBM tape library products.
| Developer(s) | HP |
|---|---|
| Stable release | 1.1.0 / November 29, 2010 |
| Development status | Active |
| Written in | C |
| Operating system | Linux, Mac OS X |
| Platform | x64, Intel x86 - 32-bit |
| License | GNU Lesser General Public License |
| Website | www.hp.com/go/ltfs |
The HP Linear Tape File System (HP LTFS) is a free open source software application which provides a self-describing tape format based on the LTFS specification from the LTO Technology Provider Companies.
HP LTFS provides users with the ability to access files on an LTO-5 tape using the same commands and operations as that of a disk drive. With HP LTFS, users can share content across heterogeneous systems without the need for separate application software to read or write data to tape. Because HP LTFS is an open format, users can be sure that their data is accessible without the need for any proprietary software, making it particularly suited for long-term data archive.
| Developer(s) | Quantum Corporation |
|---|---|
| Operating system | Linux, Mac OS X |
| License | GNU Lesser General Public License |
| Website | www.quantum.com/ltfs |
By Quantum Corporation. Linux and Mac OS X are supported.