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What is a 3-2-1 Backup Strategy?

Justifying the need for data backup within any enterprise today should be a simple task. However, determining an organization’s best backup strategy might not be as easy. There are numerous hardware and software options to choose from, and a myriad of suggested policies and procedures describing how to use them.

The 3-2-1 rule, attributed to photographer Peter Krogh, follows these requirements:

  • 3 Copies of Data – Maintain three copies of data—the original, and at least two copies.
  • 2 Different Media – Use two different media types for storage. This can help reduce any impact that may be attributable to one specific storage media type. It’s your decision as to which storage medium will contain the original data and which will contain any of the additional copies.
  • 1 Copy Offsite – Keep one copy offsite to prevent the possibility of data loss due to a site-specific failure

The 3-2-1 rule should be considered a baseline. However, many organizations mandate more than three copies of managed data. Some may split the data between one or more production, backup (possibly using an alternative media), and disaster recovery sets (potentially offsite). Others may have more unique requirements, but the 3-2-1 rule is as good a place to start as any.