I recall years ago a conversation about national archives type groups running into the problem of the amount of data divided by the transfer rate being either longer than the lifetime of the media, or longer than the refresh window.

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>.

Hm. I'm of a different opinion based on decades long observations/experience. For one, the environment they seem to operate in is toxic. As seems to be the general case in data-centers, not only their special pods. This has been impressively demonstrated by Brendan Gregg - Shouting in the Datacenter https://www.youtube.com/watch?v=tDacjrSCeq4

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.

Oh Thank You. I will look into it.

I think hard disk drives, tapes and cds have a pretty good offline life, and should last a lifetime if you, like me, are not planning on surviving to advanced age.

CDs and DVD degrade over time, I think this is primarily those with home recording CD / DVD-Rs. I am not sure what the difference is with Factory made CDs or DVDs like Music CD or DVD from Playstation 2 but those seems to be fine. I think I need to look this up that you have brought it to my attention.

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?

Be very aware -- SSD must be plugged in otherwise they may lose data after a few years.

The time varies with temperature. Search for SSD data retention for more info.

The JEDEC standard is the one to read.