You should use something like CrystalDiskMark and check in on your drives every once in a while.
Very old, decade and a half data that does not necessarily apply to today's drives from Google said
S.M.A.R.T. only gave warning of impending disk failure half of time time. Ideally look for software that constantly checks reported disk health and alerts you if there's a problem.
In the Linux and probably BSD worlds and perhaps ported to macOS and/or Windows there's the smartd daemon from smartmontools, which also gives you a neat command line interface to this data including the ability to do self-checks, although avoid doing the long ones very often because today's disks have very limited official total amount of data you can read or write per year.
Just confirmed for Seagate's best and biggest five year warranty enterprise drives they still have less than 550TB per year, a limit they've had for years no matter the capacity of the drive, but one for some time you have to read
the product manual to find out. Consumer drives typically have significantly lower official limits, and three or fewer years warranties speak for themselves.
For actual archival storage - Accept nothing less than M-Disc BDXL.
M-DISC the company is half a decade dead.
Once upon a time, and maybe still today their one layer DVDs were supposed to be very good, but I've never been able to find out if that technology is used in multi-layer BD's with that marketing label, and I have serious doubts it would work for the semi-transparent layers.
And last time I checked a few years ago these discs were made by CMC in India, all the good companies dropped out of the consumer market, one or two Japanese ones still make media using this technology for enterprises but it's not compatible with the consumer drives we can easily buy.
E: Any cloud recommendations are silly. The amount of data loss and service interruptions that happen in that space is much more significant than people realize.
Who gives a damn about service interruptions for backup and emergency, very expensive retrieval?
I have heard AWS S3 isn't as reliable as they claim, and the whole company is so poorly run it would be crazy to put all your eggs in that one basket, sooner or latter they might have a catastrophic failure from humans or code. The advice all sane people give is to use two or more completely different cloud vendors. So maybe AWS and Microsoft Azure so your total monthly at rest cost is $3/TiB.
