I'm still looking for a full-fledged backup and archiving solution that has the following characteristics:
0) error-correction (not just detection!)
1) end-to-end encryption
2) deduplication
3) compression
4) cross-platform implementations
5) (at least one) user interface
6) open source
Both Borg [0] and Restic [1] have long standing open issues for error-correction, but seem to consider it off strategy. I find that decision kind of strange, since to me the whole purpose of a backup solution is to restore your system to a correct state after any kind of incident.
My current solution is an assembly of shell scripts that combine borg with par2, but I'm rather unhappy with it. For one, I trust my home-brewn solution rather faintly (i.e. similar to `don't roll your own crypto` I think there should be an adagium `don't roll your own back-up solutions`). In addition I think an error-correcting mechanism should be available also for the less technology-savvy.
Paper/master thesis/nerd snipe idea: does availability of Reed-Salomon information of unencrypted files weaken the encryption of their encrypted counterparts?
I have yet to find a conclusive analysis on how well RAR with recovery works for different failure modes.
I mean I can guess it works pretty well for single-bit flips, but how about burst errors, how long can those be? Usually you want to have protection from at least 1 or 2 filesystem blocks, which can be 4 or 8k or even more, depending on the file system. How about repeating error patterns, data deletions, etc.?
Personally I use 7zip for compression and par2[0] for parity.
[0] https://en.wikipedia.org/wiki/Parchive