Practically speaking, with a modern hard drive, do we need to worry about a bit rot goes undetected on a hard drive when read? Assuming that the bit rot occurs on the disk, not in memory or elsewhere.
This question is different from Is bit rot on hard drives a real problem? What can be done about it? . This question specifically asks about undetectable bit rot, while the other one asks bit rot on hard drives generally.
with a modern hard drive, do we need to worry about a bit rot goes undetected on a hard drive?
Yes. Bit rot occurs when data remains unread for a long time and magnetic bits have sufficient time to deteriorate beyond the drive's capability to compensate the error. The chance is rather small but does exist.
when read?
When data is read, the drive is smart enough to fix the error, ie. move deteriorated but still readable data to a reserve block.
Actually undetectable bit rot requires multiple error bits to cancel each other out, so that the drive does not notice the rot in its internal error detection. That is extremely unlikely given modern drives with their data encoding and error compensation, so you can just ignore the possibility.
