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.
Related posts:
Create Recoverable archives with QuickparZip File Recovery with Object Fix Zip
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Bin, Cue, Img and Iso files explained
Zip Repair
9 Responses to “Par2 Files Explained”
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[...] of course but most of the time you have partial files that can be recovered. This is a like the Par2 file system which I have written about earlier in this [...]
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[...] Par2 files Explained [...]
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[...] nicht mehr lesbar sind. ICE ECC nutzt ein ähnliches System um Dateien wiederherzustellen wie Quick Par über das ich schon vorher berichtet [...]
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[...] this time with data for error correction. The most popular tools are QuickPar for creating PAR/PAR2 files and ICE ECC, being a mightier and faster tool. By adding an 3-25% overhead you can not only verify [...]
I use the newsgroups (Usenet) extensively. And I have come to the conclusion that if someone’s RAR posts are incomplete, their PAR posts are usually off kilter too. I find that it is generally a waste of time downloading incomplete RAR files. That’s why I use the AndroidNews from http://www.sb-software.com/android/ as this program shows me if a RAR series is incomplete and I can just ignore it. Even with high speed 9mbps connection, it still take half an hour for some large programs to download. And trying to fiddle with RAR/PAR recovery afterwards is really really really annoying :(
i am with mewshosting.com 100 days retention and just about all my download have missing or incomplete rars, my latest download (6.80gb) had incomplete in every rar and all par2 were damaged, i had to bin the lot as i had 970 missing blocks, oh, and the files were only up 42 days.
So much for paying a premium sever when you hagve to bin about half of your downloads, a waste of time and a waste of my money.
forgot to mention when using binsearch it shows all files are there and i have 2 downloaders, Grabit and Newsleecher so i doubt that both the downloaders are faulty.
Par2 Files Explained
I sort of understand the use of QuickPar but, using your example above, how do you now create the .avi file so you can view it?
Chris the Par files are only there to assure file integrity. You unpack the files normally with an unpacker of your choice.
I never use it for usenet, nobody wants to use that crap. I use it for backups on DVD, much more useful.