Ask ten new self-hosters how they back up their data. Most will say one word: RAID.

They're wrong. And that misunderstanding is why so many home servers die a sudden, total death.

What RAID actually does

RAID mirrors or spreads your data across multiple drives. If one disk fails, the others keep running. That's it. RAID protects against hardware failure of a single drive — nothing else.

That sounds like a backup. It isn't. Here's why.

The 4 disasters RAID does nothing about

  • You delete a file by accident. RAID instantly deletes it from every mirrored drive. Gone.
  • Ransomware or a bad script corrupts your data. RAID faithfully copies the corruption everywhere.
  • Two drives fail at once. Common when disks come from the same batch and age together.
  • Your house floods, burns, or gets robbed. Every drive sits in the same box.

RAID keeps your server online. A backup keeps your data alive. Those are different jobs.

The rule that actually works: 3-2-1

Memorize this. It's the whole game:

  • 3 copies of your data
  • 2 different types of storage (e.g. internal drive + external USB)
  • 1 copy kept off-site

If your setup can't tick all three boxes, you don't have a backup. You have a wish.

A beginner setup you can build this weekend

  1. Copy 1 — your live data. The files on your server right now.
  2. Copy 2 — local backup. Plug in a cheap external USB drive. Use a free tool like Kopia or Duplicati to run a nightly backup to it. Both have simple web interfaces and encrypt your data before it's stored.
  3. Copy 3 — off-site. Point the same tool at a cheap cloud bucket (Backblaze B2, Storj) or a spare drive you keep at a relative's house. Encrypted, so nobody but you can read it.

That's 3 copies, 2 media types, 1 off-site. Done.

The privacy angle nobody mentions

When you back up to the cloud, your files leave your home. Never trust a provider to encrypt them for you. Encrypt them before they leave.

Kopia and Duplicati both do client-side encryption by default. You set a passphrase, and the cloud only ever sees scrambled blobs. Lose the passphrase and even you can't read them — so write it down and store it somewhere safe, offline.

Test it — or it doesn't count

An untested backup is a rumor. Once a month, pick one random file and restore it from your off-site copy. If it opens, you're safe. If it doesn't, you found out on your terms — not during a real disaster.

Today's takeaway: Plug in one external drive tonight and set up a nightly encrypted backup. RAID is not a backup — a copy you can restore is.