Backup and recovery
The 3-2-1 backup rule, in plain English
Backup professionals have a simple rule of thumb for making sure data survives almost anything. It is worth knowing even if someone else runs your backups.
1 min readExplainer
The short version
Three copies of your data, on two kinds of storage, with one somewhere else. A simple rule that still works.
The rule
- 3 copies of your data: the original and two backups.
- 2 different kinds of storage: for example, a backup device in the office and cloud storage, so one failure cannot take out both.
- 1 copy somewhere else: away from the office, so a fire, flood or theft cannot destroy everything.
The modern addition
Ransomware changed the rule. Attackers now look for backups and delete or encrypt them before they strike. So one copy should also be:
- Unchangeable for a set period (often called immutable), or
- Offline, disconnected from your network and accounts.
Some people now write the rule as 3-2-1-1-0: the extra 1 for a copy attackers cannot change, and the 0 for zero errors when you test a restore.
Questions to ask about your backups
- How many copies are there, and where are they?
- Could someone with an administrator password delete all of them?
- When was a restore last tested, and did it work?
- How long would it take to get your most important system running again?
Talk to us about your technology
Tell us what you run today and what is getting in the way. We will get back to you about how we can help.