.par2 file extension

.par2

RAR archive parity file. Also known as a Parchive or Parity Archive Volume set file.

Files of type .par2 are parity files which sometimes accompany .rar compressed archive files. A .par2 file does not itself contain any compressed data, but contains parity information which can be used to repair a corrupt .rar archive file (or a missing file where the compressed archive is split across several files.

There may be more than one .par2 file for a given RAR archive, and these can be used individually although recovery is then only possible if the appropriate .par2 file is available. It is important to note that it might not be necessary to have all .par2 files available in order to recover a corrupt RAR archive. The following is taken directly from the Parity Volume Specification 2.0:

PAR 2.0 files should always end in ".par2". For example, "file.par2". If a file contains recovery slices, the ".par2" should be preceded by ".volXX-YY" where XX to YY is the range of exponents for the recovery slices. For example, "file.vol20-29.par2". More than 2 digits should be used if necessary. Any exponents that contain fewer digits than the largest exponent should be preceded by zeros so that all filenames have the same length. For example, "file.vol075-149.par2". Exponents should start at 0 and go upwards.

cf .par, .p01, .p02.

For more information see:

www.quickpar.org.uk - QuickPar data verification and repair using PAR2.
www.techsono.com/faq/par.html - .par2 (and .par) files explained in plain English.
http://parchive.sourceforge.net - Information about Parity Archive (PArchive) Volume sets.
http://parchive.sourceforge.net/docs/specifications/parity-volume-spec/article-spec.html - The .par2 file specification.

Can you add to this? Do you know of any applications not already listed which will work with .par2 files, view .par2 files or open .par2 files? Are you able to contribute any additional reference information or file format information about .par2 files or have you spotted any errors or omissions? If so please let us know by emailing us at feedback@cryer.co.uk - Thank you.