Knowledge Base · Storage & backup
Is RAID a backup?
By Tiny · how I pick
No. RAID keeps your data available when one drive dies. It doesn't protect you from the things that usually destroy data: deleting the wrong folder, ransomware, corruption, theft, or a fire. Those hit every drive at once.
RAID keeps a server running. Backups keep your data safe. You need real, separate backups either way.
Words you'll see in this guide
- RAID: storing data across several drives so one can fail without losing anything. It protects against a dead drive, and it isn't a backup.
- NAS: network-attached storage. A box of drives on your home network that every device can save to.
- Rebuild: copying data onto a replacement drive after one in a RAID set fails.
- Ransomware: malicious software that locks your files and demands payment to unlock them.
- 3-2-1 backup: three copies of your data, on two kinds of storage, with one copy somewhere other than your house.
What RAID does
RAID spreads your data across several drives. If one fails, everything keeps running, and you can swap in a new drive without shutting down. That's useful for a server you want to stay online. What it protects against is one drive's hardware failing, and that's all.
What RAID can't protect you from
- Deleting the wrong file. RAID copies the deletion to every drive instantly.
- Ransomware or malware. It locks your files across the whole set at once.
- Corruption or a bad save. The damaged file gets copied to every drive too.
- Theft, fire, flood, or a power surge. Every drive sits in the same box in the same room.
- A failed rebuild. Replacing a dead drive puts heavy work on the others, and a second one can fail partway through.
In all of these, your "copies" are really one copy in one place.
- 3 copies of anything important
- on 2 different types of storage
- with 1 copy outside your house
Should I use RAID at all?
Sure, if staying online matters to you and you have the drives. Just don't let it replace backups. If you have to choose where to spend, an off-site backup protects far more of your data than extra drives in one box.
Quick answers
Is RAID a backup?
No. RAID keeps your data available when one drive fails. It doesn't protect against accidental deletion, ransomware, corruption, theft, or fire, because those affect every drive at once.
Why is RAID not considered a backup?
A backup is a separate, independent copy. RAID keeps one live copy spread across drives in the same machine, so anything that deletes or damages a file does it on every drive.
What is the 3-2-1 backup rule?
Keep 3 copies of anything important, on 2 different types of storage, with 1 copy off-site. Your home server or NAS counts as one copy.
Where to go next
- Setting up storage? See the best NAS for beginners, and whether you need a NAS or a mini PC.
- Need the off-site copy? The free and paid picks page covers backup services.
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