Parity Volume Set - Revision history

Anonymoususer852: /* Discussion */ Modified bracket usage for reference link to Par3 specification to avoid causing display issues in References section.

2025-08-09T09:16:04Z

‎Discussion: Modified bracket usage for reference link to Par3 specification to avoid causing display issues in References section.

Anonymoususer852: /* Discussion */ Add an interesting note to proposed 3.0 specification that has yet to be finalized and implemented.

2025-08-09T09:12:03Z

‎Discussion: Add an interesting note to proposed 3.0 specification that has yet to be finalized and implemented.

Anonymoususer852: Add status to par3 and the link to par3cmdline.

2025-08-09T09:01:27Z

Add status to par3 and the link to par3cmdline.

Anonymoususer852: /* Sample files */ Par1 files also has .par, like Par2, except .par is ambiguous.

2025-08-08T09:34:40Z

‎Sample files: Par1 files also has .par, like Par2, except .par is ambiguous.

Anonymoususer852: /* Sample files */ Link fixes.

2025-08-08T09:18:35Z

‎Sample files: Link fixes.

Anonymoususer852: Merge data from Parchive. Use Template:Magic instead. Add more links, references and information.

2025-08-08T08:56:37Z

Merge data from Parchive. Use Template:Magic instead. Add more links, references and information.

Parchivist: /* Software */

2023-08-21T20:43:22Z

‎Software

Jsummers at 14:37, 21 September 2019

2019-09-21T14:37:57Z

Johanvanderknijff at 16:22, 25 May 2016

2016-05-25T16:22:58Z

Johanvanderknijff: Created page with "{{FormatInfo |formattype=electronic |thiscat=Error detection and correction |extensions={{ext|par}}, {{ext|pxx}}, {{ext|par2}}, {{ext|pa3}} }} '''Parity Volume Set''' (also k..."

2016-05-25T16:16:17Z

Created page with "{{FormatInfo |formattype=electronic |thiscat=Error detection and correction |extensions={{ext|par}}, {{ext|pxx}}, {{ext|par2}}, {{ext|pa3}} }} '''Parity Volume Set''' (also k..."

New page

{{FormatInfo
|formattype=electronic
|thiscat=Error detection and correction
|extensions={{ext|par}}, {{ext|pxx}}, {{ext|par2}}, {{ext|pa3}}
}}

'''Parity Volume Set''' (also known as '''parity archive''' or '''parchive''') is a file format for storing redundant data for one or more input files. These data can be used to repair the input files if they get damaged. The error correction is based on the [[Reed-Solomon_error_correction|Reed-Solomon algorithm]]. Three versions of the format exist: ''Par1'', ''Par2'' and ''Par3''. The ''Par3'' format never made it beyond the proposal stage, but it is used by the MultiPar tool.

== Identification ==

A '''Par1''' file starts with the byte sequence <code>50 41 52 00 00 00 00 00</code>, which corresponds to the ASCII text string <code>PAR</code>, followed by 5 nul bytes. A '''Par2''' file starts with bytes <code>50 41 52 32 00 50 4B 54</code>, which corresponds to ASCII text string<code>PAR2</code>, followed by a null byte and the text string <code>PKT</code>. Finally, a '''Par3''' file usse the 4-byte sequence <code>50 41 33 00</code> (<code>PA3</code> followed by a null byte).

== Specifications ==
* [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec-1.0/article-spec.html Parity Volume Set Specification v1.0]
* [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html Parity Volume Set Specification 2.0]
* [https://web.archive.org/web/20100911002706/http://hp.vector.co.jp/authors/VA021385/par3_spec_prop.htm proposal for Parchive Specification 3.0]

== Software ==

* [https://github.com/Parchive/par2cmdline par2cmdline] (Linux par2 tool)
* [http://hp.vector.co.jp/authors/VA021385/ MultiPar] (Windows, GUI)

== Sample files ==

== Links ==
* [[Wikipedia:Parchive]]
* [http://www.techsono.com/usenet/files/par2 Par2 Files Explained in Plain English]

@@ Line 27: / Line 27: @@
    The other part of "support any linear code" is supporting codes beside Reed-Solomon. Reed-Solomon has excellent data protection, but is slow to compute. LDPC and sparse random matrices will speed things
    up dramatically, with a slight increase in errors that cannot be recovered from.
-<ref>[https://parchive.github.io/doc/Parity_Volume_Set_Specification_v3.0.html#design-goals Parity Volume Set Specification 3.0 [2022-01-28 ALPHA DRAFT] - GitHub]</ref>
+<ref>[https://parchive.github.io/doc/Parity_Volume_Set_Specification_v3.0.html#design-goals Parity Volume Set Specification 3.0 (2022-01-28 ALPHA DRAFT) - GitHub]</ref>
 == Identification ==

← Older revision		Revision as of 09:12, 9 August 2025
Line 14:		Line 14:

	Modern <code>Par2</code> software can take advantage of GPU to speed up recovery file creation.<ref>[https://github.com/Yutaka-Sawada/MultiPar/issues/40 GPU Acceleration via par2j64.exe??? Is it possible? How do I do it? #40 - MultiPar - GitHub]</ref><ref>[https://github.com/Parchive/par2cmdline/pull/176 Added support for GPU acceleration (CUDA) on recovery file creation. #176 - par2cmdline - GitHub]</ref>		Modern <code>Par2</code> software can take advantage of GPU to speed up recovery file creation.<ref>[https://github.com/Yutaka-Sawada/MultiPar/issues/40 GPU Acceleration via par2j64.exe??? Is it possible? How do I do it? #40 - MultiPar - GitHub]</ref><ref>[https://github.com/Parchive/par2cmdline/pull/176 Added support for GPU acceleration (CUDA) on recovery file creation. #176 - par2cmdline - GitHub]</ref>
		+
		+	While <code>Par3</code> has yet to be finalized as of writing in 2025, the "2022-01-28 ALPHA DRAFT" specifications addresses interesting flaws that has existed since its conception:
		+	Major differences from Parchive 2.0 are:
		+	...(redacted for brevity)
		+	* replace MD5 hash (It is both slow and less secure.)
		+	...(redacted for brevity)
		+
		+	Part of "support any linear code" is to fix the major bug in Parchive 2.0. Parchive 2.0 did not do Reed-Solomon encoding as it promised. There was a major mistake in the paper that Parchive 2.0 relied on.
		+	The problem manifested as a bug in Parchive 1.0 and, while Parchive 2.0 reduced its occurrence, it did not fix the problem. Parchive 2.0 did not use an always invertible matrix; it essentially used a random
		+	matrix, which (luckily) is invertible with high probability. Parchive 3.0 fixes that bug.
		+
		+	The other part of "support any linear code" is supporting codes beside Reed-Solomon. Reed-Solomon has excellent data protection, but is slow to compute. LDPC and sparse random matrices will speed things
		+	up dramatically, with a slight increase in errors that cannot be recovered from.
		+	<ref>[https://parchive.github.io/doc/Parity_Volume_Set_Specification_v3.0.html#design-goals Parity Volume Set Specification 3.0 [2022-01-28 ALPHA DRAFT] - GitHub]</ref>

	== Identification ==		== Identification ==

@@ Line 6: / Line 6: @@
 }}
-'''Parity Volume Set''' (also known as '''parity archive''' or '''parchive''') is a file format for storing redundant data for one or more input files. These data can be used to repair the input files if they get damaged. The error correction is based on the [[Reed-Solomon_error_correction|Reed-Solomon algorithm]]. Three versions of the format exist: ''Par1'', ''Par2'' and ''Par3''. The ''Par3'' format never made it beyond the proposal stage, but it is used by an old version of MultiPar tool.<ref>[https://github.com/Yutaka-Sawada/MultiPar/issues/46#issuecomment-948179335 Par3 support? #46 - MultiPar - GitHub]</ref>
+'''Parity Volume Set''' (also known as '''parity archive''' or '''parchive''') is a file format for storing redundant data for one or more input files. These data can be used to repair the input files if they get damaged. The error correction is based on the [[Reed-Solomon_error_correction|Reed-Solomon algorithm]]. Three versions of the format exist: ''Par1'', ''Par2'' and ''Par3''. The ''Par3'' format is in "near-final form"<ref>[https://github.com/Parchive/par3cmdline/commit/4c1b780ebe9f083eccf8a668435613c348eae313 Commit 4c1b780 - 2022-01-29 - par3cmdline - GitHub]</ref>, it is used by an old version of MultiPar tool,<ref>[https://github.com/Yutaka-Sawada/MultiPar/issues/46#issuecomment-948179335 Par3 support? #46 - MultiPar - GitHub]</ref> as well as <code>par3cmdline</code>.<ref>[https://github.com/Parchive/par3cmdline par3cmdline - GitHub]</ref>
 == Discussion ==
@@ Line 68: / Line 68: @@
 ** [https://pypar2.fingelrest.net/ PyPar2]
 ** [https://github.com/Parchive/par2cmdline par2cmdline]
 == Sample files ==

@@ Line 71: / Line 71: @@
 == Sample files ==
 === Par1 sample files ===
-See [https://discmaster.textfiles.com/search?mode=deep&extension=p01&format=parityArchiveVolumeSet Search results with p01 extensions - Discmaster.textfiles.com]
+See [https://discmaster.textfiles.com/search?q=%22par%22&mode=deep&extension=par&format=parityArchiveVolumeSet Search results with par extensions - Discmaster.textfiles.com] for sample <code>Par1</code> files.
-<code>Par1</code> files are usually distributed in a set, beginning with <code>.p01</code> and the number increments for each and every related <code>Par1</code> archive.<ref>[https://web.archive.org/web/20250612232413/https://www.techsono.com/files/par2 Par2 Files Explained in Plain English - Internet Archive copy]</ref>
+<code>Par1</code> files are usually distributed in a set, containing <code><name>.par</code> and <code>.p<num></code>, where <code><name></code> is the name of the file, typically to be created as a parity archive of, and <code><num></code> is an integer that starts with <code>01</code>, incrementing for each and every related <code>Par1</code> archive.<ref>[https://web.archive.org/web/20250612232413/https://www.techsono.com/files/par2 Par2 Files Explained in Plain English - Internet Archive copy]</ref>
-See Also: [https://discmaster.textfiles.com/search?mode=deep&extension=p02&format=parityArchiveVolumeSet Search results with p02 extensions - a continuation of same parity archive files from those with p01 extensions - Discmaster.textfiles.com]
+See Also:
 === Par2 sample files ===
@@ Line 81: / Line 83: @@
 These files are usually distributed in a set, containing <code><name>.par2</code> and <code><name>.vol<numA>+<numB>.par2</code>, where <code>name</code> is the name of the file, typically to be created as a parity archive of, and <code><num></code> is an incrementing number, and is often starts with <code>0</code> for <numA>.<ref>[https://web.archive.org/web/20250612232413/https://www.techsono.com/files/par2 Par2 Files Explained in Plain English - Internet Archive copy]</ref>
 == Links ==

@@ Line 71: / Line 71: @@
 == Sample files ==
 === Par1 sample files ===
-See [https://discmaster.textfiles.com/search?mode=deep&extension=p01&format=parityArchiveVolumeSet Search results with p01 extensions]
+See [https://discmaster.textfiles.com/search?mode=deep&extension=p01&format=parityArchiveVolumeSet Search results with p01 extensions - Discmaster.textfiles.com]
 <code>Par1</code> files are usually distributed in a set, beginning with <code>.p01</code> and the number increments for each and every related <code>Par1</code> archive.<ref>[https://web.archive.org/web/20250612232413/https://www.techsono.com/files/par2 Par2 Files Explained in Plain English - Internet Archive copy]</ref>
-See Also: [https://discmaster.textfiles.com/search?mode=deep&extension=p02&format=parityArchiveVolumeSet Search results with p02 extensions - a continuation of same parity archive files from those with p01 extensions]
+See Also: [https://discmaster.textfiles.com/search?mode=deep&extension=p02&format=parityArchiveVolumeSet Search results with p02 extensions - a continuation of same parity archive files from those with p01 extensions - Discmaster.textfiles.com]
 === Par2 sample files ===

@@ Line 3: / Line 3: @@
 |subcat=Error detection and correction
 |extensions={{ext|par}}, {{ext|pxx}}, {{ext|par2}}, {{ext|pa3}}
 }}
-'''Parity Volume Set''' (also known as '''parity archive''' or '''parchive''') is a file format for storing redundant data for one or more input files. These data can be used to repair the input files if they get damaged. The error correction is based on the [[Reed-Solomon_error_correction|Reed-Solomon algorithm]]. Three versions of the format exist: ''Par1'', ''Par2'' and ''Par3''. The ''Par3'' format never made it beyond the proposal stage, but it is used by the MultiPar tool.
+'''Parity Volume Set''' (also known as '''parity archive''' or '''parchive''') is a file format for storing redundant data for one or more input files. These data can be used to repair the input files if they get damaged. The error correction is based on the [[Reed-Solomon_error_correction|Reed-Solomon algorithm]]. Three versions of the format exist: ''Par1'', ''Par2'' and ''Par3''. The ''Par3'' format never made it beyond the proposal stage, but it is used by an old version of MultiPar tool.<ref>[https://github.com/Yutaka-Sawada/MultiPar/issues/46#issuecomment-948179335 Par3 support? #46 - MultiPar - GitHub]</ref>
 == Identification ==
@@ Line 11: / Line 19: @@
 A '''Par1''' file starts with the following byte sequence:
-<code>50 41 52 00 00 00 00 00</code>
+{{magic|50 41 52 00 00 00 00 00}}
 This corresponds to the ASCII text string <code>PAR</code>, followed by 5 null bytes.
@@ Line 17: / Line 25: @@
 A '''Par2''' file starts with the bytes:
-<code>50 41 52 32 00 50 4B 54</code>
+{{magic|50 41 52 32 00 50 4B 54}}
 This corresponds to ASCII text string <code>PAR2</code>, followed by a null byte and the text string <code>PKT</code>.
@@ Line 23: / Line 31: @@
 Finally, a '''Par3''' file can be identified by the following 4-byte sequence:
-<code>50 41 33 00</code>
+{{magic|50 41 33 00}}
 This corresponds to the text string <code>PA3</code>, followed by a null byte.
 == Specifications ==
-* [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec-1.0/article-spec.html Parity Volume Set Specification v1.0]
+{|
-* [http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html Parity Volume Set Specification 2.0]
+|'''Specification version'''
-* [https://web.archive.org/web/20100911002706/http://hp.vector.co.jp/authors/VA021385/par3_spec_prop.htm proposal for Parchive Specification 3.0]
+|'''SourceForge/Internet Archive link'''
 == Software ==
+* Windows
-* [https://github.com/Parchive/par2cmdline par2cmdline] (Linux par2 tool)
+** [http://www.quickpar.org.uk/index.htm QuickPar] (par2, GUI)
-* [http://hp.vector.co.jp/authors/VA021385/ MultiPar] (Windows, GUI)
+** [https://github.com/Yutaka-Sawada/MultiPar MultiPar] (GUI)
-* [http://www.quickpar.org.uk/ QuickPar] (Windows, par2, GUI)
+* Mac
 == Sample files ==
 == Links ==
 * [[Wikipedia:Parchive]]
-* [http://www.techsono.com/usenet/files/par2 Par2 Files Explained in Plain English]
+* [http://www.techsono.com/usenet/files/par2 Par2 Files Explained in Plain English] (Broken link) <sup>[https://web.archive.org/web/20250612232413/https://www.techsono.com/files/par2 [Internet Archive copy]]</sup>

@@ Line 1: / Line 1: @@
 {{FormatInfo
 |formattype=electronic
-|thiscat=Error detection and correction
+|subcat=Error detection and correction
 |extensions={{ext|par}}, {{ext|pxx}}, {{ext|par2}}, {{ext|pa3}}
 }}