Seems like tar, with internal checksums (instead of external checksums or FEC). I'd just stick with tar and add some par2 blocks if you are worried about bitrot.
Unlike tar/dar, FSArchiver also creates the file-system when it extracts the data to partitions
https://pthree.org/2014/04/01/protect-against-bit-rot-with-p...
Basically, you take a normal TAR file and creates external parity files that can be used to recover data in the case of bitrot. Something like this would have been great to have on a few data files I had to retrieve from tape that ended up with a bit flip somewhere in the network > disk > tape > disk process.
However, it doesn't look like the program is maintained anymore...
http://parchive.sourceforge.net/
> DISCLAIMER: This project web space is not actively mantained and is presented here for archive purposes. However some project members still montior the project mailings lists if you have questions. (sic)
The last release was in 2004 (Wikipedia says it was active until 2015, but I don't see that).
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
And I guess, more importantly, your first link (well, [2]), is also the source used for at least the Debian package, so it's at least more up to date!
Why?