ISO/IEC 20919:2016

INTERNATIONAL ISO/IEC
STANDARD 20919
First edition
2016-04-01
Information technology — Linear
Tape File System (LTFS) Format
Specification
Technologies de l’information — Spécification du format de système
de fichier à bande magnétique
Reference number
ISO/IEC 20919:2016(E)
©
ISO/IEC 2016

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ISO/IEC 20919:2016(E)

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ii © ISO/IEC 2016 – All rights reserved

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ISO/IEC 20919:2016(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are
members of ISO or IEC participate in the development of International Standards through technical
committees established by the respective organization to deal with particular fields of technical
activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other
international organizations, governmental and non‐governmental, in liaison with ISO and IEC, also
take part in the work. In the field of information technology, ISO and IEC have established a joint
technical committee, ISO/IEC JTC 1.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for
the different types of document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject
of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent
rights. Details of any patent rights identified during the development of the document will be in the
Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does
not constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO's adherence to the World Trade Organization (WTO)
principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
ISO/IEC 20919:2016 was prepared by SNIA and adopted, under the PAS procedure, by joint
technical committee ISO/IEC JTC 1, Information technology, in parallel with its approval by national
bodies of ISO and IEC.
© ISO/IEC 2016 – All rights reserved iii

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ISO/IEC 20919:2016(E)
Linear Tape File System (LTFS) Format
Specification
Version 2.2.0
This document has been released and approved by the SNIA. The SNIA believes that
the ideas, methodologies and technologies described in this document accurately
represent the SNIA goals and are appropriate for widespread distribution. Suggestions
for revision should be directed to http://www.snia.org/feedback/
SNIA Technical Position
December 21, 2013
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ISO/IEC 20919:2016(E)
LTFS Format Specification
Revision History
Revision Date Sections Originator: Comments
2.1.0 May 18, 2012 Entire Document David Pease LaTeX version contributed by IBM
2.2.0 rev a January 15, 2013 Entire document Arnold Jones Converted to Microsoft Word
2.2.0 rev b March 15, 2013 Entire document Carl Madison Edits/Additions per TWG
2.2.0 rev c April 4, 2013 Entire document Carl Madison Edits/Additions per TWG F2F
2.2.0 rev d May 7, 2013 Entire document Carl Madison Diagram Replacement/edits
2.2.0 rev e May 28, 2013 Entire document Carl Madison F2F edits, misc edits
2.2.0 rev f July 16, 2013 Entire document Carl Madison Edits per TWG
2.2.0 rev g July 23, 2013 Entire document Carl Madison Edits per TWG F2F
2.2.0 rev h July 29, 2013 Entire document Carl Madison Edits per TWG
2.2.0 rev i July 30, 2013 Entire document Carl Madison Edits per TWG 7/30/13 mtg
2.2.0 rev j August 13, 2013 Entire document Carl Madison Edits per TWG 8/13/13 mtg
2.2.0 rev k August 27, 2013 Entire Document Carl Madison Edits per TWG 8/27/13 mtg.
2.2.0 SNIA December 21, 2013* Entire Document Carl Madison *2.2.0 rev k formatted as a SNIA
Technical Technical Position after SNIA
Position membership approval.
March 14, 2013**
**Additional editorial revisions
Suggestion for changes or modifications to this document should be sent to the SNIA Linear Tape File
System Technical Work Group at http://www.snia.org/feedback/.
Changes between v1.0 and v2.0.0
• Incremented version number to 2.0.0 and updated date to March 11, 2011.
• Improvements in specification text to remove ambiguity and clarify intention of the specification.
These changes were made at several locations throughout the document.
• Improvements to clarify description of MAM parameters in Section 9 Medium Auxiliary Memory.
• Removed reference to a specific version of the Unicode standard in Section 6.5 Name pattern format.
This removes any requirement to use specific versions of Unicode support code in an
implementation.
• Improved description of Name pattern format to remove ambiguity in Section 6.5 Name pattern
format.
• Added description of LTFS Format specification version numbering in Section 2.1 Versions.
• Updated XML Schema for Label and Index to match version number format in Annex A and
Annex B.
• Added specification of minimum and recommended blocksize value for LTFS Volumes to Section
7.1.2 LTFS Label.
• Added definition of allowed version numbers to Section 7.1.2 LTFS Label and Section 8.2 Index.
• Added definition of fileoffset tag in Section 8.2 Index.
• Extended description in Section 5 Data Extents to support addition of fileoffset tag and associated
functionality.
• Added definition of highestfileuid tag in Section 8.2 Index.
• Added definition of fileuid tag in Section 8.2 Index.
2 SNIA Technical Position LTFS Format Specification V2.2.0
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ISO/IEC 20919:2016(E)
LTFS Format Specification
• Added definition of backuptime tag in Section 8.2 Index.
• Incremented version number in Application Client Specific Information (ACSI) structure shown in 9.3
Use of Volume Coherency Information for LTFS. This increment allows identification of LTFS
Volumes written with a LTFS v1.0 compliant implementation. A widely used v1.0 implementation
wrote ambiguous ACSI values due to an implementation bug.
• Added definition of extended attributes in the ltfs.* namespace in Annex C.
• Added description for handling unknown XML tags in Index to Section 8.2.10 Managing LTFS
Indexes.
Changes between v2.0.0 and v2.0.1
• Incremented specification version number to 2.0.1.
• Updated specification date to August 17, 2011.
• Expanded historical record of changes between revisions of LTFS Format Specification.
• Improved description of constraints for two Indexes having the same generation number in Section
4.4.1 Generation Number to make it clear that differences in access time values is permitted between
Indexes that are otherwise except for self pointer and index pointer values.
• Added note in Section 4.4.1 Generation Number to explicitly state that Index generation numbers may
increase by integer values other than 1.
• Expanded description of the ltfs.sync extended attribute in Annex C . The expanded description
explicitly states that this extended attribute triggers a sync of the in-memory data to the storage
media. That is, the operation is analogous to a POSIX sync operation.
Changes between v2.0.1 and v2.1.0
• Incremented specification version number to 2.1.0.
• Updated specification date to October 18, 2012.
• Added definition of symlink tag in Section 8.2 Index.
• Added example of symlink tag use in Annex E (informative) Complete Example LTFS Index.
• Added symlink tag to Annex B.
• Added description of “ltfs.vendor.X.Y” extended attribute namespace in Annex C .
• Added description of software metadata section in Annex C.
• Added description of drive metadata section in Annex C.
• Added ”ltfs.labelVersion” extended attribute in Annex C.
• Added ”ltfs.indexVersion” extended attribute in Annex C
• Added ”ltfs.mediaEncrypted” extended attribute in Annex C .
• Improved description of ”ltfs.mediaStorageAlert” extended attribute in Annex C.
Changes between v2.1.0 and v2.2.0
• Incremented specification version number to 2.2.0.
• Updated specification date to July 16, 2013.
• Changed “2010” to “2013” in XML examples.
• Editorial Cleanup.
LTFS Format Specification V2.2.0 SNIA Technical Position 3
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ISO/IEC 20919:2016(E)
LTFS Format Specification
• Changed “extentinfo” definition in Section 8.2 Index.
• Changed “symlink” definition in Section 8.2 Index.
• Added additional paragraph to “symlink” definition in Section 8.2 Index.
• Added general comments at start of Section 9 Medium Auxiliary Memory.
• Added Section 9.4 Use of Host-type Attributes for LTFS.
• Removed Section 9 Certification from document.
• Added “ltfs.mamBarcode” extended attribute in Annex C.4 Volume Metadata.
• Added “ltfs.mamApplicationVendor” extended attribute in Annex C.4 Volume Metadata.
• Added “ltfs.mamApplicationVersion” extended attribute in Annex C.4 Volume Metadata.
• Added “ltfs.mamApplicationFormatVersion” extended attribute in Annex C.4 Volume Metadata.
• Added new Annex F Interoperability Recommendation and added File Spanning and File Permissions
subsections
Usage
The SNIA hereby grants permission for individuals to use this document for personal use only, and for
corporations and other business entities to use this document for internal use only (including internal
copying, distribution, and display) provided that:
1. Any text, diagram, chart, table or definition reproduced must be reproduced in its
entirety with no alteration, and,
2. Any document, printed or electronic, in which material from this document (or any
portion hereof) is reproduced must acknowledge the SNIA copyright on that material,
and must credit the SNIA for granting permission for its reuse.
Other than as explicitly provided above, you may not make any commercial use of this document, sell any
or this entire document, or distribute this document to third parties. All rights not explicitly granted are
expressly reserved to SNIA.
Permission to use this document for purposes other than those enumerated above may be requested by
emailing tcmd@snia.org. Please include the identity of the requesting individual and/or company and a
brief description of the purpose, nature, and scope of the requested use.
Contacting SNIA
SNIA Web Site
Current SNIA practice is to make updates and other information available through their web site at
http://www.snia.org.
SNIA Address
Requests for interpretation, suggestions for improvement and addenda, or defect reports are welcome.
They should be sent via the SNIA Feedback Portal at http://www.snia.org/feedback/ or by mail to the
Storage Networking Industry Association, 4360 ArrowsWest Drive, Colorado Springs, Colorado 80907,
U.S.A.
4 SNIA Technical Position LTFS Format Specification V2.2.0
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ISO/IEC 20919:2016(E)
LTFS Format Specification
Disclaimer
The information contained in this publication is subject to change without notice. The SNIA makes no
warranty of any kind with regard to this specification, including, but not limited to, the implied warranties of
merchantability and fitness for a particular purpose. The SNIA shall not be liable for errors contained
herein or for incidental or consequential damages in connection with the furnishing, performance, or use
of this specification.
Suggestions for revisions should be directed to http://www.snia.org/feedback/.
Copyright © 2013-2014 Storage Networking Industry Association.
Acknowledgements
The SNIA LTFS Technical Working Group, which developed and reviewed this specification, would like to
recognize the significant contributions made by the following members:

EMC Corporation. . Don Deel
Hewlett-Packard . . Chris Martin
IBM. . David Pease
.................................................. ................ Ed Childers
NetApp. . David Slik
Oracle Corporation. . Matthew Gaffney
................................................. ................. Carl Madison
Quantum Corporation. . Paul Stone
SNIA. . Arnold Jones


LTFS Format Specification V2.2.0 SNIA Technical Position 5
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ISO/IEC 20919:2016(E)
LTFS Format Specification
Contents
1 Introduction . 10
2 Scope . 11
2.1 Versions . 11
2.2 Conformance . 12
3 Definitions and Acronyms . 13
3.1 Definitions . 13
3.2 Acronyms . 15
4 Volume Layout . 16
4.1 LTFS Partitions . 16
4.2 LTFS Constructs . 16
4.3 Partition Layout . 17
4.4 Index Layout . 18
5 Data Extents . 20
5.1 Extent Lists . 20
5.2 Extents Illustrated . 20
5.3 Files Illustrated . 22
6 Data Formats . 26
6.1 Boolean format . 26
6.2 Creator format . 26
6.3 Extended attribute value format . 26
6.4 Name format . 27
6.5 Name pattern format . 27
6.6 String format . 27
6.7 Time stamp format . 28
6.8 UUID format . 28
7 Label Format . 29
7.1 Label Construct . 29
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ISO/IEC 20919:2016(E)
LTFS Format Specification

8 Index Format . 32
8.1 Index Construct . 32
8.2 Index . 32
9 Medium Auxiliary Memory . 43
9.1 Volume Change Reference . 43
9.2 Volume Coherency Information . 44
9.3 Use of Volume Coherency Information for LTFS . 44
9.4 Use of Host-type Attributes for LTFS . 46
Annex A (normative) LTFS Label XML Schema . 48
Annex B (normative) LTFS Index XML Schema . 50
Annex C (normative) Reserved Extended Attribute definitions . 53
C.1 Software Metadata . 53
C.2 Drive Metadata . 53
C.3 Object Metadata . 53
C.4 Volume Metadata . 54
C.5 Media Metadata. 55
Annex D (informative) Example of Valid Simple Complete LTFS Volume . 58
Annex E (informative) Complete Example LTFS Index . 59
Annex F (normative) Interoperability Recommendations . 63
F.1 Spanning Files across Multiple Tape Volumes in LTFS . 63
F.2 File Permissions in LTFS . 66

LTFS Format Specification V2.2.0 SNIA Technical Position 7
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ISO/IEC 20919:2016(E)
LTFS Format Specification
List of Figures
Figure 1 — LTFS Partition .16
Figure 2 — Label Construct .16
Figure 3 — Index Construct .17
Figure 4 — Partition Layout .17
Figure 5 — Complete partition containing data .18
Figure 6 — Back Pointer example .19
Figure 7 — Extent starting and ending with full block .21
Figure 8 — Extent starting with full block and ending with fractional block .21
Figure 9 — Extent starting and ending in mid-block .21
Figure 11 — File contained in two Data Extents .22
Figure 10 — File contained in a single Data Extent .22
Figure 12 — Shared Blocks example .23
Figure 13 — Sparse files example .24
Figure 14 — Shared data example .24
Figure 15 — Label construct .29
Figure 16 — Index Construct .32
Figure D. 1 — Content of a simple LTFS volume .58
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ISO/IEC 20919:2016(E)
LTFS Format Specification

List of Tables
Table 1 — Version elements .11
Table 2 — Version comparisons .12
Table 3 — Extent list entry starting and ending with full block .21
Table 4 — Extent list entry starting with full block and ending with fractional block .21
Table 5 — Extent list entry starting and ending in mid-block .22
Table 6 — Extent list entry for file contained in a single Data Extent .22
Table 7 — Extent list entry for a file contained in two Data Extents .22
Table 8 — Extent lists for Shared Blocks example .23
Table 9 — Extent list for sparse files example .24
Table 10 — Extent lists for shared data example .25
Table 11 — Creator format definitions .26
Table 12 — Prohibited characters for name format .27
Table 13 — Characters which should be avoided for name format .27
Table 14 — Time stamp format .28
Table 15 — VOL1 Label Construct .29
Table 16 — Volume Coherency Information .44
Table 17 — ACSI format for LTFS .45
Table 18 — Relevant Host-type Attributes for LTFS .46
Table 19 — Example of Host-type Attributes .47
Table C. 1 — Reserved extended attribute definitions: Software metadata .53
Table C. 2 — Reserved extended attribute definitions: Drive metadata .53
Table C. 3 — Reserved extended attribute definitions: Object metadata .54
Table C. 4 — Reserved extended attribute definitions: Volume metadata .54
Table C. 5 — Reserved extended attribute definitions: Media metadata .55


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ISO/IEC 20919:2016(E)
LTFS Format Specification


1 Introduction
This document defines a Linear Tape File System (LTFS) Format separate from any
implementation on data storage media. Using this format, data is stored in LTFS Volumes. An
LTFS Volume holds data files and corresponding metadata to completely describe the directory
and file structures stored on the volume.
The LTFS Format has these features:
• An LTFS Volume can be mounted and volume content accessed with full use of the data
without the need to access other information sources.
• Data can be passed between sites and applications using only the information written to an
LTFS Volume.
• Files can be written to, and read from, an LTFS Volume using standard POSIX file
operations.
The LTFS Format is particularly suited to these usages:
• Data export and import.
• Data interchange and exchange.
• Direct file and partial file recall from sequential access media.
• Archival storage of files using a simplified, self-contained or “self-describing” format on
sequential access media.
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ISO/IEC 20919:2016(E)
LTFS Format Specification

2 Scope
This document defines the LTFS Format requirements for interchanged media that claims LTFS
compliance. Those requirements are specified as the size and sequence of data blocks and file marks on
the media, the content and form of special data constructs (the LTFS Label and LTFS Index), and the
content of the partition labels and use of MAM parameters.
The data content (not the physical media) of the LTFS format shall be interchangeable among all data
storage systems claiming conformance to this format. Physical media interchange is dependent on
compatibility of physical media and the media access devices in use.
NOTE: This document does not contain instructions or tape command sequences to build the LTFS structure.
2.1 Versions
This document describes version 2.2.0 of the Linear Tape File System (LTFS) Format Specification.
The version number for the LTFS Format Specification consists of three integer elements separated by
period characters of the form M.N.R, where M , N , and R are positive integers or zero. Differences in the
version number between different revisions of this specification indicate the nature of the changes made
between the two revisions. Each of the integers in the format specification are incremented according to
Table 1.
Table 1 — Version elements
Element Description
M
Incremented when a major update has been made to the LTFS Format
Specification. Major updates are defined as any change to the on-media format or
specification semantics that are expected to break compatibility with older
versions of the specification.
N Incremented when a minor update has been made to the LTFS Format
Specification. Minor updates are defined as any change to the on-media format or
specification semantics that is not expected to break compatibility with older
versions of the specification that have the same value for M in the version
number.
R
Incremented when textual revisions are made to the LTFS Format Specification.
Textual revisions are defined as revisions that improve the clarity of the
specification document without changing the intent of the document. By definition,
minor changes do not alter the on-media format or specification semantics.

NOTE 1: When any
...