If it's for storage on optical disks I'm rather fond of dvdisaster (https://en.wikipedia.org/wiki/Dvdisaster https://en.wikipedia.org/wiki/Dvdisaster) which wil

If it's for storage on optical disks I'm rather fond of dvdisaster (https://en.wikipedia.org/wiki/Dvdisaster https://en.wikipedia.org/wiki/Dvdisaster) which will fill up spare space on a disk with redundant data, specifically distributing it across the surface to prevent defects in one area leading to unrecoverable data. Seems to have become unmaintained though, which is worrying.