@DarkMahesvara Random bitrot on a large files or a collection of files occurs fairly commonly due deficiencies in RAM, HDD and SDD technology.

Most likely you don't have ECC RAM and HDD's+SDD's also allocate the minimum amount of space possible to ECC, plus data density is so small, the reading of charges and turning those charges into bytes is a statistical operation.

Usually such bitflips go unnoticed, as are you usually going to notice a small colour change in a chunk in a PNG or video or a bitflip in an elf file in struct padding bytes, or a slight CPU instruction change in a function that doesn't end up causing a change in execution by chance?


It looks like rsync copied the file correctly, but when qbitorrent compared the sha1 hashes of all the chunks, it found one with a bitflip.

What's good about bittorrent is that as you're seeding a torrent, each chunk is automatically checked and corrected (if needed) as they're seeded, plus even if the torrent isn't very popular, you just need to hit verify in the torrent client every few months to automatically correct any bitflips.

Btrfs is the filesystem attempt to provide something similar, but for recovery to work a second drive in RAID with a duplicate of the corrupted block is needed.