分类: LINUX
2005-10-14 11:45:47
QuickPar is a utility for creating Parity Volumes using the Reed Solomon algorithm. For details of the algorithm used, see the website at SourceForge.
Parity Volumes may be used to verify that a set of files have not been corrupted, or to reconstruct damaged files (providing that you have a sufficient quantity of Parity Volumes to match the missing or damaged files).
QuickPar uses the PAR version 2.0 specification. You can read about the differences between PAR version 1.0 and PAR version 2.0 .
What is the difference between the PAR 1.0 specification and the PAR 2.0 specification? | |
PAR 1.0 has a number of limitations:
PAR 2.0 either completely removes or significantly reduces these limitations:
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So how exactly does PAR 2.0 remove all of these limitations? | |
The limitations of PAR 1.0 are all due to the fact that it operates on "whole" files. PAR 2.0 operates by "virtually" splitting the files you wish to protect into many smaller "slices" (or blocks) of data. PAR 2.0 then processes these virtual slices in the same way that PAR 1.0 would process whole files. The resulting blocks of recovery data are the same size of these slices, and for convenience, many of them will be placed in a single PAR file. |
How does using a PAR 2.0 program differ from a PAR 1.0 program? | |
A PAR 2.0 program will work equally well with a single 800MB file or with hundreds of files of varied sizes. It is not necessary either to split large files, or to archive large numbers of small files. This makes the files directly useable without the need to rejoin them or unpack them first. This means that it is possible place PAR files on an SVCD to protect a video. With PAR 1.0, the only option you needed to specify when creating PAR files is how much recovery data you wish to create. With PAR 2.0, you must also specify how many slices the files will be virtually divided into. Using a larger number of smaller slices allows more accurate detection of errors in files and reduces the amount or recovery data required to achieve a succesful repair. |