We still dont have some cheap Data Storage that last for a life time. My friend were showing me photos of her daughter from 10 years ago and most of them had it "backup" on a DVD. I couldn't quite bring myself to explain to her about DVD life time.
In the latter case you are going straight from floppy to DVD, skipping over CD. In the former case you are doing data recovery operations on aging CDR media. It’s a mess.
And it makes me wonder about the relative speed of disk duplication solutions versus backup solutions. That is to say, if I can produce 3 backups in roughly the same time as one, maybe I should be making mirrored data transfers. And then shipping one to <atmospherically stable location> And another to <politically stable location>.
Besides that I'd guess the electricity there isn't that 'clean' either.
At small scale/SOHO-use similar factors apply. If you pack them in the densest possible way for your data-hoarding needs in systems with shoddy power supply units you are asking for trouble. Similar things may apply to shiny network attached storage gadgets from the common brands.
In addition your body walking/stomping on flexible grounds makes them shake, as do wobbly desks. So put them in BIG and well ventilated cases with good power supplies, and put these where they don't shake. Or on dampers, like 2 tennis balls cut in half for 4 dampers.
I know, it's inconvenient, but that's how it is.
But do HDD last longer if they are unplugged. And only start up when they are needed? In that case wouldn't an NAS putting HDD to sleep most of the time would prolong the life time of HDD?
The time varies with temperature. Search for SSD data retention for more info.
The JEDEC standard is the one to read.