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Article · Jan 29, 2016

What is the 3-2-1 backup rule?

What is 3-2-1 backup?

Color illustration depicting a laptop computer and data storage device.

The 3-2-1 rule is a classic rule for keeping your files safe and has been adopted by almost all backup services. Put simply, the rule lays out best practices for business continuity:

  • Keep at least 3 copies of your data
  • Keep the backed-up data on 2 different storage types
  • Keep at least 1 copy of the data offsite

If you’re looking into backup and recovery strategies, you’re probably going to hear the phrase “3-2-1 backup” come up a lot. You’ll hear it from most IT consultants and IT pros as well as many backup vendors, who will speak about their products in terms of 3-2-1 compliance.

3-2-1 backup strategy breakdown

Simple image for #3 in a circle. Keep at least three (3) copies of your data

That includes the original copy and at least two backups.

Simple image for #2 in a circle. Keep the backed-up data on two (2) different storage types

The chances of having two failures of the same storage type are much better than for two completely different types of storage. Therefore, if you have data stored on an internal hard drive, make sure you have a secondary storage type, such as external or removable storage, or the cloud.

Simple image for #1 in a circle. Keep at least one (1) copy of the data offsite

Even if you have two copies on two separate storage types but both are stored onsite, a local disaster could wipe out both of them. Keep a third copy in an offsite location, like the cloud. After all, if there’s a fire in the server room it won’t matter how many backups you have if they’re all stored next to each other.

Is the 3-2-1 rule a good backup strategy?

The 3-2-1 backup rule is considered a best practice because it ensures that you’ll have a copy of your data no matter what happens. Multiple copies prevent you from losing the only copy of your data. Multiple locations ensure that there is no single point of failure and that your data is safe from disasters such as fires and floods.

We recommend whenever speaking to a backup vendor to make sure that you ask them how their backup solution fits with 3-2-1 compliance.

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Ryan Harnedy

IT Community Manager

Ryan Harnedy is the IT Community Manager for Carbonite. He blogs about technology, IT trends, and best practices for SMB IT pros.

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