The difficulty of 3-2-1 increases as your data size goes up.
For me, the only sane thing to do is partitioning.
My first group would be data that if I were to lose it would cause great pain. I keep the size of this group as small as possible. A few hundred megs or less. You have a live copy, a backup on a USB thumb stick or drive, and a copy you email someone or snail mail a USB drive. It's simple to deal with. It has to be, because it's critical.
My second group is data that is important but not a serious threat to me. Photos and videos, mostly. This second group is where the headache starts and logistics, cost, and time become an issue. Offsite backup is either running to the bank deposit box (time consuming), or upload to cloud (also time consuming, and expensive). Containing the bit rot becomes a futile exercise. Especially considering most people aren't running ECC RAM and end-to-end ZFS with redundancy (for recovery) requires significant expertise and time. Parchive files are the best bet for most people.
Finally, my third group. I have a NAS with a simple mirrored ZFS setup. Two huge drives. I'll probably add a 3rd drive for added redundancy. There is no backup. This data I don't care that much about. I'd hate to lose it. But I'd hate backing it up much more. I don't live for my data, my data lives for me.
You have to ruthlessly prune data that you care to keep. Just like the burden of owning a boat or an overly large house, there is a burden to too much data you care about. The mistake a lot of people make is treating all data the same. Then they end up with terabytes of data of unequal importance and get sloppy protecting the tiny amount of data that truly matters.
For me, the only sane thing to do is partitioning.
My first group would be data that if I were to lose it would cause great pain. I keep the size of this group as small as possible. A few hundred megs or less. You have a live copy, a backup on a USB thumb stick or drive, and a copy you email someone or snail mail a USB drive. It's simple to deal with. It has to be, because it's critical.
My second group is data that is important but not a serious threat to me. Photos and videos, mostly. This second group is where the headache starts and logistics, cost, and time become an issue. Offsite backup is either running to the bank deposit box (time consuming), or upload to cloud (also time consuming, and expensive). Containing the bit rot becomes a futile exercise. Especially considering most people aren't running ECC RAM and end-to-end ZFS with redundancy (for recovery) requires significant expertise and time. Parchive files are the best bet for most people.
Finally, my third group. I have a NAS with a simple mirrored ZFS setup. Two huge drives. I'll probably add a 3rd drive for added redundancy. There is no backup. This data I don't care that much about. I'd hate to lose it. But I'd hate backing it up much more. I don't live for my data, my data lives for me.
You have to ruthlessly prune data that you care to keep. Just like the burden of owning a boat or an overly large house, there is a burden to too much data you care about. The mistake a lot of people make is treating all data the same. Then they end up with terabytes of data of unequal importance and get sloppy protecting the tiny amount of data that truly matters.