Par2 Files Explained

Par2 Files are common on the Usenet today.They are not that common on the Internet in general and I can’t think of a location where I encountered them except for the Usenet. Par2 Files can be used to repair broken archives. That is the basic explanation of course, the technical is a little bit more complicated. Lets use a example to make it clearer. Let us assume that you have downloaded a number of rar files (.rar, r01, r02 and so on) that can be unpacked to create the file test.avi which has a size of 700 Megabytes.

Let us further assume that some of the rar files have been uploaded incompletely to the Usenet which happens from time to time. It would not be possible to extract test.avi because of the broken files in the archive. Par2 Files are fixers. They analyze the blocks of each rar archive and post back if it is complete, incomplete or missing. Every Par2 file can be used to fix a certain number of blocks that corresponds to the amount of blocks of the rar files.

All you need to have is enough par2 files that can fix the missing blocks in the rar files to repair these files. The real beauty of this system is that you can fix any broken rar file with any par2 file. You do not need to look for the complete rar file, all you need is to download the par2 files which are normally posted with the rar files in the same newsgroup.

I’m using the free software Quickpar to test and repair rar archives that I have downloaded from the Usenet.

The first screenshot shows tested files using Quickpar. It shows that 96 blocks are missing and are needed to repair the archive so that it can be extracted. After downloading enough Par2 files to be able to repair the archive Quickpar automatically repairs the damaged files.

The second screenshot displays three par2 files that can be used to repair the damaged files. This process usually does not take more than a few minutes and you can extract the archive when the operation has been finished.