3 ms·
I've had a few experiences trying to recover data from old hard drives or even tape drives. The general experience was that either it works perfectly or the dri
by technion 4y ago
I've had a few experiences trying to recover data from old hard drives or even tape drives. The general experience was that either it works perfectly or the drive is covered in bad sectors and large chunks are unreadable. I don't dispute bitrot exists but there does seem to be an awful lot of discussion on the internet about an issue that is not not the most likely failure mode.
- jmillikin 4y agoBitrot is generally from two sources: * At the sector level in physical media (tapes, disk drives, flash). The file will be largely intact, but 4- or 8-KiB chunks of it will be zero'd out. * At the bit level, when copying goes wrong. Usually this is bad RAM, sometimes a bad network device, very occasionally a bad CPU. You'll see patterns like "every 64th byte has had its high bit set to 1". In both cases, the only practical option is to have multiple copies of the file, plus some checksum to decide whether a copy is "good". Files on disk can be restored from backup, bad copies over the network can be detected by software and re-transmitted.
- loeg 4y ago> In both cases, the only practical option is to have multiple copies of the file, plus some checksum to decide whether a copy is "good". Well, or FEC blocks (eg, par2). Might be insufficient for the every 64th byte case, but probably enough for a few zeroes sectors.