The Linear Tape File System (LTFS) is a file system that allows files stored on

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magnetic ...

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 International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

, was adopted by the LTO Consortium in 2010.

History

Magnetic tape data storage Magnetic-tape data storage is a system for storing digital information on magnetic tape using digital recording. Tape was an important medium for primary data storage in early computers, typically using large open reels of 7-track, later ...

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 Interoperability is a characteristic of a product or system to work with other products or systems. While the term was initially defined for information technology or systems engineering services to allow for information exchange, a broader de ...

and tapes might or might not contain an index of their content. In

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

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 the NAB show in 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 file In computer science, a sparse file is a type of computer file that attempts to use file system space more efficiently when the file itself is partially empty. This is achieved by writing brief information (metadata) ''representing'' the empty blo ...

s; 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. LTFS v2.2.0 was released in December 2013. It was the first version to become an ISO standard (20919:2016). LTFS v2.5.1 was released in May 2019. It became the second version of the ISO standard (20919:2021). Version 2.5 contained fairly major updates, as it was the first version to define Incremental (sparse) Indexes.

Format specification

Th
ISO/IEC 20919:2021
standard defines the LTFS Format requirements for interchanged media that claims LTFS compliance. It defines the data format, independent of the physical storage media and the software commands format, to make data truly interchangeable. The ISO standard was prepared by SNIA. It is based on LTFS v2.5.1, and was adopted to ISO by a joint technical committee ISO/IEC JTC 1 ''Information Technology''. The SNIA workgroup continues to develop LTFS and release updates. 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: * correctly read media that was compliant with any prior version * write media that is compliant with the version they claim compliance with

SNIA Technical Work Group

In August 2012, SNIA announced that it was forming a TWG (Technical Work Group) to continue technical development of the specification. LTFS Format Specification v 2.1 is the baseline for the technical work and standards accreditation process; SNIA LTFS TWG members include HP,

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and

Quantum In physics, a quantum (: quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a property can be "quantized" is referred to as "the hypothesis of quantization". This me ...

Nature

While LTFS can make a tape appear to behave like a disk, it does not change the fundamentally sequential nature of tape. Files are always appended to the end of the tape. If a file is modified and overwritten or removed from the volume, the associated tape blocks used are not freed up, they are simply marked as unavailable and the used volume capacity is not recovered. Data is only deleted and capacity recovered if the whole tape is reformatted. In spite of these disadvantages, there are several uses case where LTFS formatted tape is superior to spinning disk and other data storage technology. While LTO seek times can range from 10 to 100 seconds, the streaming data transfer rate can match or exceeded spinning-disk data transfer rates. For example, LTO-9 is capable of a continuous transfer speed of 400 MB/s while spinning HDDs typically max out at 200–250 MB/s for the first 30% of their capacity. Additionally, LTO cartridges are easily transportable and hold far more data than most other removable data storage format. The ability to copy a large file or a large selection of files (up to 1.5TB uncompressed data for LTO-5, and 18TB for LTO-9) to an LTFS formatted tape allows easy exchange of data with a collaborator, or the saving of an archival copy. Since LTFS is an open standard, LTFS formatted tapes are usable by a wide variety of computing systems and operating systems, avoiding the incompatibilities caused by previous proprietary LTO filesystems.

Implementations

Tape drives manufacturers often offer two different editions, one for ''Single Drives'' and one for ''Tape Libraries'', based on the ''LTFS Reference Implementation''.

IBM Linear Tape File System - Single Drive Edition

The

Linear Tape File System - Single Drive Edition, (initially released as "IBM Long Term File System"), allows tapes to be formatted as an LTFS volume, and for these volumes to be mounted - and users and applications access files and directories stored on the tape directly, including

drag-and-drop In computer graphical user interfaces, drag and drop is a pointing device gesture in which the user selects a virtual object by "grabbing" it and dragging it to a different location or onto another virtual object. In general, it can be used to ...

of files.

IBM Linear Tape File System - Library Edition

The

Linear Tape File System - Library Edition (LTFS-LE) product allows LTFS volumes to be used in a

tape library Tape or Tapes may refer to: Material Tape is long, narrow, thin strip of material usually used to stick things together. (see also Ribbon (disambiguation): Adhesive tapes * Adhesive tape, any of many varieties of backing materials coated with ...

. Each LTFS-formatted tape cartridge in the library appears as a separate folder under the filesystem mount point and 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.

Oracle's StorageTek Linear Tape File System, Open Edition

's free open source StorageTek Linear Tape File System (LTFS), Open Edition software is claimed to be the first to store 8.5TB (native capacity) on a single cartridge. It supports Oracle’s midrange StorageTek LTO 5 and LTO 6 tape drives from HP and IBM as well as Oracle’s StorageTek T10000C and T10000D tape drives.

Oracle's StorageTek Linear Tape File System, Library Edition

Oracle’s StorageTek LTFS-LE software offering supports the StorageTek SL8500 Modular Library System, the StorageTek SL3000 Modular Library System, and the StorageTek SL150 Modular Tape.

HP Linear Tape File System

The HP Linear Tape File System (HP LTFS) is HP's implementation. It is a free open source software application.

Quantum Linear Tape File System

Quantum Corporation provides an LTFS product with Linux and macOS support. Windows versions of Quantum LTFS utilities were discontinued and are out-of-life since July 2023; Quantum recommends Windows users to use TeraCopy instead. The Scalar LTFS Appliance was a file system that presented a Quantum tape library as an NAS share. This appliance made files viewable as if they resided on a local disk and allowed users to drag and drop files directly to and from a tape cartridge.

LTFS compatible products

DDS Tape Drives

* HPE: ** DAT-160 and DAT-320

Enterprise Tape Drives

* IBM: ** TS1140, TS1150, TS1155, TS1160 and TS1170 * Oracle (Sun/StorageTek): ** T10000C and T10000D

LTO Tape Drives

* HPE, IBM, Quantum, and Tandberg: ** from LTO-5 to LTO-9

Appliances and ISVs (Independent Software Vendors) supporting LTFS

A full set of vendors are listed at LTO website.

LTFS projects

* '' Thought Equity Motion'' is executing a major film digitization and preservation project for the EYE Film Institute Netherlands. The project involves scanning more than 150 million discrete DPX files and storing them on LTO Gen5 using the LTFS format. More than 1

petabyte The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable un ...

of film will be scanned and archived over two years (2010–2012).

Industry recognition

* IBM LTFS technology received a Pick Hit Award from Broadcast Engineering at NAB 2011. * IBM and FOX Networks received an Engineering Emmy Award in 2011 for a project that uses LTFS to store, exchange, and archive video content. * IBM received the 2011 Hollywood Post-Alliance
HPA
Engineering Excellence Award.HPA Award Announcement
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Limitations

As of standard version 2.5.1, LTFS does not support hard links. When files are deleted, they become invisible to the user. However, the space occupied by a file is not freed. Because of this, it is possible to "roll back" the tape to an earlier state, in order to recover erroneously deleted (or incorrectly updated) files. To free up space a tape needs to be re-formatted.

References

External links

LTFS at LTO

LTFS at SNIA

LTFS for Dummies Book
* Implementations: ** (LTFS Reference Implementation for stand alone tape drive) *
IBM Spectrum Archive

IBM Spectrum Archive Single Drive Edition (SDE)
*
Oracle Tape Storage

Oracle Linear Tape File System, Open Edition
*
HP Linear Tape File System

HPE LTFS Software
*
Quantum Linear Tape File System

Quantum LTFS Source
* {{GitHub, ibm-research/LTFS-Data-Management Computer file systems Computer storage tape media IBM file systems