In comp.os.linux.misc Martin Gregorie wrote:

The really careful and/or paranoid will use a cycle of at least three
backup disks.


I cycle 4 disks: 3 onsite and one offsite, but nothing to do with
paranoia. I use them as short-term archive also- not just backup. I've
never had a disk failure in 20+ years that needed a true backup ("knock
on wood", as they say) but at the same time I _have_ had multiple
occasions where it has been very useful to grab a file from a month or
two previously. This due to inadvertent deletion, or looking for
previous version of the file, etc. Hence 4 disks ranging from current to
several months old has served me very well for many years.

As you might intuit, I'm not about to turn over everything I have to
Apple or Google or the like, so run my own server and take care of my
own data.

Stan