197:
most useful in version 1 where the parity volumes were much larger than the short index files. These larger parity volumes contain the actual recovery data along with a duplicate copy of the information in the index files (which allows them to be used on their own to verify the integrity of the data files if there is no small index file available).
230:
In
January 2002, Howard Fukada proposed that a new Par2 specification should be devised with the significant changes that data verification and repair should work on blocks of data rather than whole files, and that the algorithm should switch to using 16 bit numbers rather than the 8 bit numbers that
144:
is a discontinued experimental version developed by MultiPar author Yutaka Sawada. The original SourceForge
Parchive project has been inactive since April 30, 2015. A new PAR3 specification has been worked on since April 28, 2019 by PAR2 specification author Michael Nahas. An alpha version of the
196:
Because the index files were so small, they minimized the amount of extra data that had to be downloaded from Usenet to verify that the data files were all present and undamaged, or to determine how many parity volumes were required to repair any damage or reconstruct any missing files. They were
188:
With the introduction of
Parchive, parity files could be created that were then uploaded along with the original data files. If any of the data files were damaged or lost while being propagated between Usenet servers, users could download parity files and use them to reconstruct the damaged or
238:
and par2cmdline. Abandoned since 2004, Paul Houle created phpar2 to supersede par2cmdline. Yutaka Sawada created MultiPar to supersede QuickPar. MultiPar uses par2j.exe (which is partially based on par2cmdline's optimization techniques) to use as MultiPar's backend engine.
231:
PAR1 used. Michael Nahas and Peter
Clements took up these ideas in July 2002, with additional input from Paul Nettle and Ryan Gallagher (who both wrote Par1 clients). Version 2.0 of the Parchive specification was published by Michael Nahas in September 2002.
363:
A discussion on a new format started in the GitHub issue section of the maintained fork par2cmdline on
January 29, 2019. The discussion led to a new format which is also named as Par3. The new Par3 format's specification is
341:
Par2 specification supports up to 32,768 source blocks and up to 65,535 recovery blocks. Input files are split into multiple equal-sized blocks so that recovery files do not need to be the size of the largest input file.
200:
In July 2001, Tobias Rieper and Stefan Wehlus proposed the Parity Volume Set specification, and with the assistance of other project members, version 1.0 of the specification was published in
October 2001. Par1 used
219:
The recovery files had to be the size of the largest input file, so it did not work well when the input files were of various sizes. (This limited its usefulness when not paired with the proprietary RAR compression
551:, and uses Yutaka Sawada's par2j.exe as the PAR2 backend. MultiPar supports multiple languages by Unicode. The name of MultiPar was derived from "multi-lingual PAR client". MultiPar is also verified to work with
161:
was not designed to transmit arbitrary binary data. Another limitation, which was acceptable for conversations but not for files, was that messages were normally fairly short in length and limited to 7-bit
368:, but remains being an alpha draft as of January 28, 2022. The specification is written by Michael Nahas, the author of Par2 specification, with the help from Yutaka Sawada, animetosho and malaire.
326:
indicates the number of the first recovery block within the PAR2 file. If an index file of a download states that 4 blocks are missing, the easiest way to repair the files would be by downloading
360:
The Par3 specification was originally planned to be published as an enhancement over the Par2 specification. However, to date, it has remained closed source by specification owner Yutaka Sawada.
711:
The original idea behind this project was to provide a tool to apply the data-recovery capability concepts of RAID-like systems to the posting and recovery of multi-part archives on Usenet.
291:
given all of the other original files and any one of the parity volumes. Alternatively, it is possible to recreate two missing files from any two of the parity volumes and so forth.
189:
missing files. Parchive included the construction of small index files (*.par in version 1 and *.par2 in version 2) that do not contain any recovery data. These indexes contain
399:
Supports "incremental backups", where a user creates recovery files for some file or folder, change some data, and create new recovery files reusing some of the older files.
563:, and may work with other operating systems too. Although the Par2 components are (or will be) open source, the MultiPar GUI on top of them is currently not open source.
773:
526:) — Produce, verify and repair par2 files recursively, both on the command line as well as with the aid of a graphical user interface. It is available in the
798:
671:
687:
1023:
1081:
1045:
748:
723:
690:, reply #3, by Yutaka Sawada: "Their formal title are "Parity Volume Set Specification 1.0" and "Parity Volume Set Specification 2.0."
202:
678:
reply #3, by Yutaka Sawada: "Their formal title are "Parity Volume Set
Specification 1.0" and "Parity Volume Set Specification 2.0."
523:
911:
873:
126:
974:
575: — advanced par2cmdline with multithreading and highly optimized assemblercode (about 66% faster than QuickPar 0.9.1)
185:. Large files were broken up to reduce the effect of a corrupted download, but the unreliable nature of Usenet remained.
638:
777:
544:
802:
499:
449:
1007:
453:
205:
to create new recovery files. Any of the recovery files can be used to rebuild a missing file from an incomplete
1148:
1143:
1069:
667:
445:
378:
Supports packing small files into one block, as well as deduplication when a block appears in multiple files.
117:, and accidental or malicious damage. Despite the name, Parchive uses more advanced techniques (specifically
352:
Directory support is included in the PAR2 specification, but most or all implementations do not support it.
844:
365:
407:
118:
349:
is mentioned in the PAR2 specification as an option, most PAR2 implementations do not support
Unicode.
145:
PAR3 specification has been published on
January 29, 2022 while the program itself is being developed.
393:
887:
527:
596:
226:
It was strongly tied to Usenet and it was felt that a more general tool might have a wider audience.
36:
1085:
1019:
1015:
1000:
995:
389:
1049:
932:
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727:
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are capable of integrating parity data into their formats for error detection and correction:
953:
877:
223:
The recovery algorithm had a bug, due to a flaw in the academic paper on which it was based.
114:
863:
620:
1153:
1011:
675:
552:
516:
library. Does not support verifying or repair, it can currently only create PAR2 archives.
157:. Usenet was originally designed for informal conversations, and the underlying protocol,
106:
465:
1118:
178:
91:
651:– RAID levels at and above RAID 5 make use of parity data to detect and repair errors.
1137:
642:
475:
461:
275:), which is CRC type file with no recovery blocks, and a number of "parity volumes" (
190:
95:
1128:
996:"Finding movies (or TV shows): Recovering missing RAR files with PAR and PAR2 files"
591:
479:
859:
371:
The new format claims to have multiple advantages over the Par2 format, including:
153:
Parchive was intended to increase the reliability of transferring files via Usenet
79:
55:
51:
1123:
193:
that can be used to quickly identify the target files and verify their integrity.
101:
Parchive was originally written to solve the problem of reliable file sharing on
248:
67:
890:
867:
1113:
491:
122:
973:
Nahas, Michael; Clements, Peter; Nettle, Paul; Gallagher, Ryan (2003-05-11).
954:"A Tutorial on Reed-Solomon Coding for Fault-Tolerance in RAID-like Systems"
823:
626:
502:, or later. Currently merged into BlackIkeEagle's fork and maintained there.
322:
in the filename indicates how many blocks it contains, and the number after
212:
Version 1 became widely used on Usenet, but it did suffer some limitations:
154:
519:
615:
485:
578:
566:
235:
234:
Peter
Clements then went on to write the first two Par2 implementations,
206:
170:
110:
87:
700:
572:
17:
513:
505:
452:) — a concurrent (multithreaded) version of par2cmdline 0.4 using
346:
845:"Parity Volume Set Specification 3.0 [2022-01-28 ALPHA DRAFT]"
283:, etc.). Given all of the original files except for one (for example,
882:
560:
556:
531:
495:
418:
174:
102:
98:
operations that can repair or regenerate corrupted or missing data.
338:, it is identical in function to the small index file used in PAR1.
1108:
471:
169:
Various techniques were devised to send files over Usenet, such as
608:
569:(freeware) — unmaintained since 2004, superseded by MultiPar.
382:
163:
648:
403:
182:
158:
933:"Note: Correction to the 1997 Tutorial on Reed-Solomon Coding"
548:
509:
457:
414:
294:
Par1 supports up to a total of 256 source and recovery files.
1119:
Slyck's Guide To The Usenet Newsgroups: PAR & PAR2 Files
799:"PAR3 specification proposal not finished as of April 2011"
581: — First PAR implementation, unmaintained since 2001.
105:, but it can be used for protecting any kind of data from
1109:
Parchive project - full specifications and math behind it
847:. Michael Nahas, Yutaka-Sawada, animetosho, and malaire.
402:
Supports more error correction code algorithms (such as
385:
file names, file permissions, hard links and soft links.
251:
are incompatible. (However, many clients support both.)
547:(freeware) — Builds upon QuickPar's features and
512:) is a high performance, multithreaded PAR2 client and
388:
Supports embedding PAR data inside other formats, like
302:
Par2 files generally use this naming/extension system:
494:
is another multithreaded version of par2cmdline using
47:
35:
999:
375:Supports more than 2 files and more than 2 blocks.
334:is also acceptable. There is also an index file
216:It was restricted to handle at most 255 files.
688:Re: Correction to Parchive on Knowledge (XXG)
668:Re: Correction to Parchive on Knowledge (XXG)
8:
774:"Risk of undetectable intended modification"
30:
1129:UsenetReviewz's guide to opening par files
931:Plank, James S.; Ding, Ying (April 2003).
271:, the Parchive consists of an index file (
881:
1082:"contacted you, asking about sourcecode"
287:), it is possible to create the missing
660:
430:Supports hard links and symbolic links.
177:. Later Usenet software allowed 8 bit
912:"Parity Volume Set Specification v1.0"
181:, which permitted new techniques like
29:
975:"Parity Volume Set Specification 2.0"
701:"Parchive: Parity Archive Volume Set"
474: — (obsolete). Available in the
7:
749:"Question about your usage of PAR3"
460:based CPUs. It is available in the
952:Plank, James S. (September 1997).
330:. However, due to the redundancy,
140:is mature for widespread use, and
25:
876:. p. 5. sec. 2.2.
488:maintained fork by BlackIkeEagle.
94:, with the capability to perform
42:.par, .par2, .p??, (.par3 future)
1124:Guide to repair files using PAR2
1070:Working on Ubuntu 18.04 via wine
1046:"MultiPar works with PCBSD 9.0"
824:"Parchive: Parity Archive Tool"
76:Parity Volume Set Specification
869:Network News Transfer Protocol
724:"possibility of new PAR3 file"
611:conforming operating systems:
1:
910:Nahas, Michael (2001-10-14).
203:Reed–Solomon error correction
1114:Introduction to PAR and PAR2
1002:Steal this File Sharing Book
994:Wang, Wallace (2004-10-25).
639:Comparison of file archivers
318:, etc. The number after the
424:Supports empty directories.
417:hash function in Par2 with
1170:
427:Supports file permissions.
1008:San Francisco, California
247:Versions 1 and 2 of the
74:, and formally known as
456:. Only compatible with
332:filename.vol007+06.PAR2
328:filename.vol003+04.PAR2
316:filename.vol007+06.PAR2
312:filename.vol003+04.PAR2
308:filename.vol001+02.PAR2
304:filename.vol000+01.PAR2
623:, a frontend for par2.
119:error correction codes
82:system that produces
528:Python Package Index
472:Original par2cmdline
408:sparse random matrix
259:For Par1, the files
366:published on GitHub
32:
27:Type of file format
674:2014-10-14 at the
121:) than simplistic
37:Filename extension
1025:978-1-59327-050-6
864:"Character Codes"
862:(February 1986).
592:MacPAR deLuxe 4.2
61:
60:
16:(Redirected from
1161:
1097:
1096:
1094:
1093:
1084:. Archived from
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1072:
1067:
1061:
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1058:
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1048:. Archived from
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1036:
1035:
1033:
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1006:(1st ed.).
1005:
991:
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801:. Archived from
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776:. Archived from
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751:. Archived from
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726:. Archived from
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90:verification of
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1144:Archive formats
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858:Kantor, Brian;
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826:. 30 April 2015
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676:Wayback Machine
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466:par2cmdline-tbb
442:
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394:ISO disk images
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127:error detection
107:data corruption
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179:Extended ASCII
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92:data integrity
72:parity archive
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48:Type of format
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1088:on 2013-09-26
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860:Lapsley, Phil
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805:on 2014-03-09
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462:FreeBSD Ports
459:
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413:Replaced the
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136:is obsolete,
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19:
1090:. Retrieved
1086:the original
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1065:
1054:. Retrieved
1050:the original
1040:
1029:. Retrieved
1001:
989:
978:. Retrieved
968:
957:. Retrieved
947:
936:. Retrieved
926:
915:. Retrieved
905:
894:. Retrieved
868:
853:
839:
828:. Retrieved
818:
807:. Retrieved
803:the original
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782:. Retrieved
778:the original
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757:. Retrieved
753:the original
743:
732:. Retrieved
728:the original
718:
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704:. Retrieved
695:
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390:ZIP archives
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132:As of 2014,
131:
100:
83:
80:erasure code
75:
71:
63:
62:
56:archive file
52:Erasure code
1014:. pp.
486:par2cmdline
480:par2cmdline
249:file format
191:file hashes
125:methods of
68:portmanteau
1138:Categories
1092:2013-09-21
1056:2012-02-27
1031:2009-09-24
980:2009-10-29
959:2009-10-29
938:2009-10-29
917:2017-06-19
896:2009-10-29
830:2020-05-20
809:2012-07-01
784:2012-07-01
759:2012-07-01
734:2012-07-01
706:2009-10-29
656:References
627:GPar2 2.03
621:PyPar2 1.4
530:system as
478:system as
464:system as
171:uuencoding
155:newsgroups
86:files for
381:Supports
345:Although
672:Archived
633:See also
586:Mac OS X
567:QuickPar
545:MultiPar
532:par2deep
524:LGPL-3.0
520:par2deep
446:par2+tbb
435:Software
243:Versions
236:QuickPar
207:download
111:disc rot
88:checksum
78:) is an
64:Parchive
31:Parchive
18:SmartPAR
1016:164–167
641:– Some
539:Windows
514:Node.js
347:Unicode
267:, ...,
149:History
115:bit rot
1154:Usenet
1022:
597:UnRarX
579:Mirror
573:phpar2
561:Ubuntu
557:TrueOS
555:under
506:ParPar
496:OpenMP
419:BLAKE3
220:tool.)
175:Base64
166:text.
123:parity
103:Usenet
609:POSIX
603:POSIX
500:GPLv2
450:GPLv2
383:UTF-8
324:"vol"
281:f.p02
277:f.p01
273:f.par
164:ASCII
1020:ISBN
874:IETF
649:RAID
559:and
553:Wine
406:and
404:LDPC
356:Par3
298:Par2
255:Par1
183:yEnc
173:and
159:NNTP
142:PAR3
138:PAR2
134:PAR1
891:977
888:RFC
878:doi
549:GUI
510:CC0
458:x86
454:TBB
415:MD5
392:or
320:"+"
84:par
70:of
66:(a
1140::
1018:.
1010::
998:.
886:.
872:.
866:.
709:.
670:,
498:,
410:).
314:,
310:,
306:,
289:f2
285:f2
279:,
269:fn
265:f2
263:,
261:f1
209:.
129:.
113:,
109:,
54:,
1095:.
1059:.
1034:.
983:.
962:.
941:.
920:.
899:.
880::
833:.
812:.
787:.
762:.
737:.
534:.
522:(
508:(
482:.
468:.
448:(
421:.
396:.
20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.