Parity Volume Set

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 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 following byte sequence:

This corresponds to the ASCII text string, followed by 5 null bytes.

A Par2 file starts with the bytes:

This corresponds to ASCII text string, followed by a null byte and the text string.

Finally, a Par3 file can be identified by the following 4-byte sequence:

This corresponds to the text string, followed by a null byte.

Specifications

 * Parity Volume Set Specification v1.0
 * Parity Volume Set Specification 2.0
 * proposal for Parchive Specification 3.0

Software

 * par2cmdline (Linux par2 tool)
 * MultiPar (Windows, GUI)

Links

 * Parchive
 * Par2 Files Explained in Plain English