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Page history last edited by PBworks 17 years, 4 months ago

From: badger <1516@box.ukf.net>

Date: Thu, 8 Mar 2007 02:05:21 -0000


File CRC check file par2 (does a similar job to MD5)



These are the recovery block volumes - only some will normally need to be downloaded as per David's notes below.













In article David Harmon says...


>> On Tue, 6 Mar 2007 05:17:42 -0000 in alt.comp.freeware, badger

>> <1516@box.ukf.net> wrote,


>>> >David or anyone, is it best to leave each vol.par2 as a separate

>>> >file on a website so a user can download just enough blocks to do

>>> >the repair ?



>> Yes. Here's how it would normally work. If you create a par set with

>> default options, you would get a group of files that look something like

>> this:


>> pl2007cd.par2 40404

>> pl2007cd.vol000+01.par2 378484

>> pl2007cd.vol001+02.par2 756868

>> pl2007cd.vol003+04.par2 1473332

>> pl2007cd.vol007+08.par2 2865956

>> pl2007cd.vol015+16.par2 5610900

>> pl2007cd.vol031+32.par2 11060484

>> pl2007cd.vol063+37.par2 12750884


>> The first of those, pl2007cd.par2, is just the block checksum

>> information; the rest of them also contain a variable number of recovery

>> blocks. The number of recovery block is the +nn.


>> The user would download the iso plus pl2007cd.par2. Checking them by

>> opening the par2 in Quickpar or par2cmdline.exe would tell if the iso

>> is OK, or if not, how many recovery blocks are needed.


>> So if it says you need 4 recovery blocks, you would go back and download

>> pl2007cd.vol003+04.par2.


>> If it says you need 18 recovery blocks, you would download

>> pl2007cd.vol001+02.par2 and pl2007cd.vol015+16.par2. (2 + 16 = 18)

>> So you don't have to download more recovery information than you really

>> needed. Then you run Quickpar again, it finds all the pieces, and puts

>> it back together for you.


>> I use par2 quite a bit when backing up files to CD or DVD media in the

>> hope that it may save me some day if the disks become flakey.

>> http://www.quickpar.org.uk/


>> Thanks for your efforts. It turns out the md5 mismatch was my goof all

>> along, so I'm all straightened out now.










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