Author Topic: PAR2 - better cleanup and ALWAYS download some blocks  (Read 5847 times)

The REAL Joe Blow

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PAR2 - better cleanup and ALWAYS download some blocks
« on: March 18, 2007, 08:44:16 AM »
I would like to be able to tell the alt.binz to:

1) ALWAYS download at enough par2 blocks to recreate one complete missing rar segment, whether it needs to or not; and

2) after cleanup, delete ONLY the corrupted redundant segments, but NOT the par2 recovery blocks.

The background/reason for the request:  I had the misfortune of a harddrive crash a year ago where a 60gb disc lost the entire FAT because of a faulty cable.  It appeared as a "Error writing to drive" message, after which all of the file and directory names were totally scrambled.

This was my main 'temp' storage drive where I dumped years worth of stuff waiting to be unrar'd and burned and the whold 60bg appeard to be toast now.  Feeling like I had nothing more to lose, successively running chkdsk /f produced 6 or 7 folders worth of FILE0001.chk->FILE9999.chk (10,000 files at a time were found, that's the most that can be stored in a folder at a time, so everytime 10000 files were found I moved them into folders and repeated till no more were found).

Now for the fortunate part - everything on this drive was multipart rar archives, and every group of rar archives had a .par2 index and enough par2 recovery blocks to reproduce at least 1 of the rar segments.  For example if a 700mb rar archive was split into 14.3mb chunks, I had at least one 15mb par2 chunk to go along with that, and everything was still rar'ed up.

It took some doing, but using a search-within-file routine I was able to identify all of the PAR2 files from the 70000 or so generically named recovered files, and then by renaming them to FILE####.par2, I was able to launch them, and they would go thru the directory looking for their missing files, and eventually they found and repaired everything that belonged with them.  Believe it or not, 100% of the 60gb was recovered this way.

BUT - if I had either unrar'ed the archives, or deleted the PAR2 recovery blocks, then the whole mess would have been toast and unuseable.

So, as a lesson learned, I NEVER unrar until actually assembling stuff to burn; I ALWAYS download enough par2 blocks to replace at least one complete missing rar segment; and I NEVER delete the par2 blocks until the files are unrar'ed and burned.

Many thanks for considering this (imho) important and useful request.  If implemented, I think it needs enough brains to be able to figure out how big the rar segments are and select the appropriate size of par2 file to download with those as per the example above.

Offline sidbib

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Re: PAR2 - better cleanup and ALWAYS download some blocks
« Reply #1 on: June 16, 2021, 09:15:56 AM »
   I was going to post my own request, but I found that the 2nd part of the VERY old request above is exactly what I was going to ask for (not part #1).

I always download and keep all of the posted par2 files (So I don't need Alt.Binz to calculate enough par2 to download as was requested in #1 above).

But I currently leave par2 cleanup turned off because I don't want Alt.Binz to delete the par2 repair blocks - just the broken files that get renamed with a .1 extension after repair is complete.
Since this is not currently an option in Alt.Binz, I manually run MultiPar for any required repairs.

The MultiPar GUI allows me to do this by having two checkboxes in the options under Automated Tasks > File Deletion:
Delete damaged files after repair
Delete recovery files after repair

and by only checking the box to delete damaged files, I get my desired behavior.

If this could be added to Alt.Binz it would allow me to automate one more step of my process. But I do realize that my method is very uncommon, so I completely understand if it is not worth the effort.
But it doesn't hurt to ask :)