[pwg]

If you are willing to sacrifice some storage space on the disk, then dvdisaster (https://en.wikipedia.org/wiki/Dvdisaster) can add extra ECC data to the disk that will allow recovery even if some percentage of the disk errors out upon read later.

Granted, if one no longer has the mechanical drive, or if the disk errors out beyond the threshold where the extra ECC can correct the errors, the data's still lost. But it (dvdisaster) does provide some protection from the "bit-rot" case where the disk slowly degrades.

[iamnothere]

Par2 is also very good for resilient storage. It uses parity files that can reconstruct bitrotted files. https://en.wikipedia.org/wiki/Parchive