I've played around with an idea - what if the data I store on the disk or in memory wasn't as stable as I'm used to? What if the bits had a probability to switch from 0 to 1 or the other way around? Here's some python code which assumes 99% stability of the bits:

https://gist.github.com/jurev/106a78ffdc7ea516ec322522d40a3755

Interesting result: if you have 8 bits it is better to take 6 data bits and 2 checksum bits than 5 data bits and 3 checksum bits, taking into account that all bits (data and checksum) are only 99% stable.

Now - who would want to implement sha256 with my fuzzy bits?