Parchive

Parchive
Filename extension
.par, .par2, .p??, (.par3 future)
Type of formatErasure code, archive file

Parchive (a portmanteau of parity archive, and formally known as Parity Volume Set Specification[1][2]) is an erasure code system that produces par files for checksum verification of data integrity, with the capability to perform data recovery operations that can repair or regenerate corrupted or missing data.

Parchive was originally written to solve the problem of reliable file sharing on Usenet,[3] but it can be used for protecting any kind of data from data corruption, disc rot, bit rot, and accidental or malicious damage. Despite the name, Parchive uses more advanced techniques (specifically error correction codes) than simplistic parity methods of error detection.

As of 2014, PAR1 is obsolete, PAR2 is mature for widespread use, and PAR3 is a discontinued experimental version developed by MultiPar author Yutaka Sawada.[4][5][6][7] The original SourceForge Parchive project has been inactive since April 30, 2015.[8] A new PAR3 specification has been worked on since April 28, 2019 by PAR2 specification author Michael Nahas. An alpha version of the PAR3 specification has been published on January 29, 2022[9] while the program itself is being developed.

  1. ^ Re: Correction to Parchive on Wikipedia, Archived 2014-10-14 at the Wayback Machine reply #3, by Yutaka Sawada: "Their formal title are "Parity Volume Set Specification 1.0" and "Parity Volume Set Specification 2.0."
  2. ^ Re: Correction to Parchive on Wikipedia, reply #3, by Yutaka Sawada: "Their formal title are "Parity Volume Set Specification 1.0" and "Parity Volume Set Specification 2.0."
  3. ^ "Parchive: Parity Archive Volume Set". Retrieved 2009-10-29. 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.
  4. ^ "possibility of new PAR3 file". Archived from the original on 2012-07-07. Retrieved 2012-07-01.
  5. ^ "Question about your usage of PAR3". Archived from the original on 2014-03-09. Retrieved 2012-07-01.
  6. ^ "Risk of undetectable intended modification". Archived from the original on 2014-03-09. Retrieved 2012-07-01.
  7. ^ "PAR3 specification proposal not finished as of April 2011". Archived from the original on 2014-03-09. Retrieved 2012-07-01.
  8. ^ "Parchive: Parity Archive Tool". 30 April 2015. Retrieved 2020-05-20.
  9. ^ "Parity Volume Set Specification 3.0 [2022-01-28 ALPHA DRAFT]". Michael Nahas, Yutaka-Sawada, animetosho, and malaire.