What is the best long-term backup solution?

What the numbers show

Counted from the threads quoted below. How we count

• This comes up 303.0× more often in Hacker News than across the site as a whole.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Buying commercial tape drives (LTO) instead of optical discs.
2. 2
   Purchasing and storing the reading hardware alongside the backup media.
3. 3
   Relying on regular data transfers to new media rather than trusting a single "permanent" format.
4. 4
   Keeping standard hard drives in an offsite location, like an office drawer.
5. 5
   Following the 3-2-1 backup rule with multiple copies across different media types
6. 6
   Keeping copies on a local PC, a physical USB drive, and multiple cloud storage platforms simultaneously

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.