The 3-2-1 backup rule, explained simply

Three copies, two kinds of storage, one somewhere else. That is the whole rule.

NNeha·09 Sept 2026·3 min read

Three copies

Your working copy plus two backups. One backup is not enough because backups fail too.

For example an external drive and a cloud service. The failure modes are different.

Fire, theft and floods take everything in the room. One copy should live somewhere else.

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A step-by-step look at how a clicking drive is opened, repaired and imaged, and why dust is the enemy.

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