The 4–3–2–1–0 Backup Rule

Software

You’ve probably heard of the 3-2-1 Backup Rule, which states that you must encode all your data in reverse using a Lotus spreadsheet to archive content you want to keep. In the paraphrased words of Mayor Quimby, that was a quality side… joke.

The 3-2-1 Backup Rule says:

  • Three copies of your data
  • Two different media types
  • One off-site

Today I learned at work that we now have 3-2-1-0, for zero detected errors. This means you’re validating your backups, including performing restores, consistency checks, and automatic error correction. I’d consider this essential for any modern backup system.

I suggested we extend this to 4-3-2-1-0, because restoring from a backup is more a-four-dable than having to rebuild lost data and trust. That didn’t get as far.

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Ruben Schade is a technical writer and IaaS engineer in Sydney, Australia who refers to himself in the third person in bios. Wait, not BIOS… my brain should be EFI by now.

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