Parity file

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Parity files are files that are created to accompany data files, and are used to preserve data integrity and assist in data recovery. They are useful when data files are transmitted or stored on less-than-perfect mediums such as newsgroup messages, satellite transmission, or optical disk. Parity files are constructed according to algorithms (such as those designed by the Parchive project at Sourceforge).

1 Overview
2 Parity
3 Parity File Archiver Software
4 See also
5 External Links

[edit] Overview

First, one or more data file are analyzed and a group of 'parity files' are built that record the structure of the files to be protected.

Later, if any of the protected files are lost, the parity files can be used to re-create the missing files.

Even if one or more of the parity files are missing, the remainder of the set can still rebuild missing original files, if there is enough of the backup present. If too many files are missing, the parity files will not have enough base data to work with.

[edit] Parity

A parity is the difference within a set of binary code. the parity of 1-0 is 1, 0-0 is 0 and 0-1 is 1, therefore lost data can be rebuilt based on the parity of a set of code.