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Comment by brnt | Hacker News Reader

Made a gui around it for keeping large filetrees (pictures, musical) healthy, have a look: https://github.com/brenthuisman/par2deep

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"This tool will generate one parity file (plus a file for the recovery blocks) per file that you protect."

Maybe I used it differently: I'd have a collection of dozens or hundreds of files, and if some small portion of those files were missing or corrupt, the recovery would draw on the overall parity files.

With this tool, I might be misreading, but I think if a single file went missing, the recovery files would only be for that single file, so recovery would be impossible.

True. It doesnt 'freeze' a filesystem. Its written to handle a tree in flux (you might move/delete files), and all you have to do it move the par2 along. Backups would protect against deletions, par2deep against bitrot.

Hi. I tried it out with some random pictures and par2deep wasnt able to generate the par2 file for one of them. The error was createdfiles_err. I used the GUI on win10, the file names are of normal length, file permissions are the same as for the others. I can send it to you for testing if you want

Sure, if you can, file an Issue on Github!

Did you try manually creating parity for that file (using par2cmdline)?

I almost did but I tried something else and found the likely reason: the file name contained an "ä". Par2deep also fails when there's a CJK character in the filename. After removing these non-ascii characters it works. But this bug is going to cause problems for many people.

Edit: filed a bug report

The joys of pre-UTF8 software :) You're right to point it out, however, the speed at which par2cmdline accepts PRs (~0/yr), consider it unfixable. I'm looking into https://github.com/akalin/gopar and this may solve this.

You are right. The way I use it is like you say.

My backups consist of compressed and encrypted archive files, which are then processed with PAR, to add redundancy that will allow the recovery of any corrupted files from the archive.

This would be useful for keeping my unraid data from rotting. I have definitely seen small bits of corruption in my multi-terabyte storage, even with ECC in place.

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