par2cmdline

I seen this mentioned a few times in the thread. While true, there are other tools (with more control) for creating recovery data, notably, parchive[1]. [1] https://github.com/Parchive/par2cmdline

One advantage of WinRAR over 7-Zip is the option to add recovery data and data parity recovery files. This can of course be accomplished on any file using PAR2 but it saved a step which some people liked. Not everyone needs this option. I create PAR files when I back up important archives to multiple external drives. par2cmdline [1] is in some Linux repositories. [1] - https://github.com/Parchive/par2cmdline [In need of a new maintainer]

Not only that but if you budget for an expected error rate of let's say 10% you can use par2 to create additional files that add that redundancy to your archives. par2 default redundancy is set to 5%. PAR2 uses Reed-Solomon Coding to perform its calculations. https://github.com/Parchive/par2cmdline

Parchive development has moved GitHub. PAR2 (libpar2/par2cmdline) continues to see active (if sporadic) maintenance. The most recent tagged release was 2020-02-09 but there've been a handful of PR's merged since. [2] PAR3 has a reference implementation and alpha spec (libpar3/par3cmdline) which is based around Blake3. [3] OG PAR (libpar/parcmdline) is legit unmaintained; the last release was 21 years ago. [1] [2]: https://github.com/Parchive/par2cmdline [3]: https://github.com/Parchive/par3cmdline [1]: https://github.com/Parchive/parcmdline/

In case you want that for a format that doesn't have it: https://github.com/Parchive/par2cmdline

If one were to bring back punch cards that are somehow updated or more advanced to hold more data then please for the love of sanity first make a machine that you can drop a massive stack of them into that will sort them. Or make it so that the reader can read them out of order and add parity data so you can lose a few cards or have a few coffee soaked unreadable cards. something along the lines of par2 [1] [1] - https://github.com/Parchive/par2cmdline

A by-the-way note for passerbys on the subject of PAR recovery records: - As usually, the Arch wiki has an excellent page on the topic: https://wiki.archlinux.org/title/Parchive - Hey, par3 is in the works: https://github.com/Parchive/par3cmdline/issues/1 - I created [Feature request / par2create] Option to regenerate par2 files if input file changed : https://github.com/Parchive/par2cmdline/issues/170

It may not exactly be what you are looking for, but if you want to protect a stable data set from bit-rot after it's been created, make sure to take a look at Parchive/par2: https://en.wikipedia.org/wiki/Parchive https://github.com/Parchive/par2cmdline/

> or maybe like Parchive par2 even has options for specifying level of redundancy. I've had good experience in recovering large corrupted files from an external drive - since then, I've incorporated it into the automated backups of my personal infrastructure. https://github.com/Parchive/par2cmdline

Here is one application that this research could be applied to: https://github.com/Parchive/par2cmdline https://en.wikipedia.org/wiki/Parchive

Thanks for the article and code. Also check out https://github.com/Parchive/par2cmdline I wish something like this was integrated into a modern and free archive format. RAR has it. RAR also got volume recovery: when creating split multi-volume archives you can also create recovery volumes - each recovery volume can replace any other one missing volume. It was a life-saver in floppy-disk times.

> One thing which concerns me is the integrity of my files. It's no good backing them up if they become corrupt without me knowing. Most of my files like photos, old emails, etc will never change and I want to keep it that way. Look into par2 files (https://github.com/Parchive/par2cmdline). Arrange your 'backup data' in some logical way, then generate par2 files for logical "groups" (i.e, per directory containing a set of files, etc.) with an amount of 'redundancy' you feel comfortable with. You can then periodically run par2 scans of the static backups to both detect changes, and to repair the changes (provided the changes are not larger than the amount of redundancy you originally requested).