3-2-1 Backup Rule

The standard rule for data redundancy:

• 3 copies of your data
• 2 different storage media types
• 1 offsite backup

Why it works

A single failure can't take out all three copies. Local drive failure? You have a second copy on a NAS. House fire? Offsite has you covered. Two different media types means a firmware bug or format vulnerability that hits one (say, all spinning HDDs) doesn't hit the other (cloud, tape, flash).

The offsite requirement is the one people skip. It's also the one that matters most when something actually goes wrong.

My current setup

• Primary: local machine
• Second copy: NAS on the local network
• Offsite: cloud (working on this)

The manual steps are the weak point. If the backup requires you to remember to do it, eventually you won't.

See also

Homelab