Michele Calgaro via trinity-users wrote:

> Harddisks do fail from time to time, that is why I suggested you could use
> more than one. The likelihood of 2 or more HD failing at the same time +
> your main HD to fail at the same time as well is super low. CD/DVD/BD
> disks could potentially fail too, get scratched, broken.....

I can second that. It seems it depends on the materials use for producing
them.
Last year I checked many backup cds from the past before throwing away. Some
written in 2002 were working and most written in 2007 were failing.
The hard drives written back then still work.
And today we have also SSDs - I don't know how long they can reliably store
information without being powered. Does someone has reference?