We are digital librarians. Among us are represented the various reasons to keep data -- legal requirements, competitive requirements, uncertainty of permanence of cloud services, distaste for transmitting your data externally (e.g. government or corporate espionage), cultural and familial archivists, internet collapse preppers, and people who do it themselves so they're sure it's done right. Everyone has their reasons for curating the data they have decided to keep (either forever or For A Damn Long Time (tm) ). Along the way we have sought out like-minded individuals to exchange strategies, war stories, and cautionary tales of failures.
HDD media are spinning disks with a magnetizable coating. The coating is relatively thick compared to how close the read heads are to the media, so if pieces of the coating come loose, the heads tend to run into them and spread them around, causing even more damage.
Using the drive will cause it to fail sooner and will continue to damage the files on the drive.
Does it just happen out of the blue that often? I have an external hdd that's like from 2011 and it still holds all the data I put in back then. I don't assume all drives should work like that, but still, I expected the older one to die much sooner than the other one.
HDDs fail this way, yes. Once one sector goes bad it can spread very quickly.
I wouldn't be surprised if you have corrupted data on that 2011 drive. You want know until you try opening a file on there.
Over the last year I opened most of the files there at least once, except for some stuff I forgot about a long time ago, but it's maybe a gig at most in total. All seemed to work fine.
If the number of bad sectors is a multiple of 8, the software is probably counting logical sectors of 512 bytes each, while the disk has physical sectors of 4096 bytes each. Each time a physical sector fails, the software counts it eight times.
Still worth replacing the disk -- a functional disk shouldn't have any bad sectors.