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Try again, but this time with subdirectories

PAR2 with subs: Multipar and alternate

I've been using it for well over a year, it works great. Was using this for a while -- it's OK, but Multipar is much better.

Or just continue to use PAR on single directories with subs placed in some type of archive (zip, 7z, tar) file.

None of these holds a candle to ZFS as a live file system, but these all work great when archiving files to DVD/BD.

Heck, I'm currently copying multiple dirs to BD and using Multipar as "only" a checksumming and renaming repair tool -- not even bothering with the file content recovery option. For that matter, I've even created a (single) disc with 300% recovery -- if I lose all of the primary files and over half of the recovery content bits, I can STILL recover the contents. (I've tested this by manually damaging the file contents. I have multiple copies in different places, too -- there are just a few static files that I do *NOT* want to lose.)

Eventually, I started using ICE ECC, http://www.ice-graphics.com/ICEECC/IndexE.html, free as in beer, to enhance my DVD backups of stuff like photos and data. IIRC, I tested it's ability to reconstruct missing files and it seemed OK at the time.

Unfortunately this software looks like it is closed source and windows only. A program to apply error correcting codes to your archived files is only useful if you still have a platform to run it on. Hopefully 15 years from now when you go to recover your files you have an old windows machine still available for use.

Yes, CDs and DVDs have error correction built in, but they don't do much if you happen to a nice scratch that follows the spin of the disk. I.e. a moderate scratch from the outside to the inside of a CD is reasonably OK for data, but a scratch the other way will kill your data much more easily.

For a while I was using PAR2, yes, the PAR2 used on USENET, to beef up the safety of my DVD backups of my home data. Unfortunately, PAR2 never really evolved to handle subdirectories properly, which mattered when I wanted an off-site backup of my digital photos.

Eventually, I started using ICE ECC, http://www.ice-graphics.com/ICEECC/IndexE.html, free as in beer, to enhance my DVD backups of stuff like photos and data. IIRC, I tested it's ability to reconstruct missing files and it seemed OK at the time.

Anyways, that's my $0.02 on Reed-Solomon for backups.

Well, you can add extra layers of error correction--in fact you can add as much error correction as you mind losing capacity from your medium. http://www.ice-graphics.com/ICEECC/IndexE.html will add extra Reed-Solomon encoding for example. Want to be able to destroy 50% of the DVD and still recover the data? No problem, add as much error correction as is worthwhile to you. You can also use PAR/PAR2 files like they do in newsgroups, or look into rateless codes.

for my long term archives i use this tool for added protection:

http://www.ice-graphics.com/ICEECC/IndexE.html

Why don't you use ICE ECC? http://www.ice-graphics.com/ICEECC/IndexE.html You can add an extra layer of error correction when you burn data on to a DVD.

Additional comments to my parent post:

Companies storing sensitive data could be expected to use software that provided error correction codes (like those generated by ICE ECC).

Laws about this would enable companies to spend the money without worrying that they were making themselves uncompetitive because of expenses. They would know their competitors must do it also.

Top managers are generally not wise about technology; they need someone to guide them toward doing the right thing.