Follow the 3-2-1 Rule of Backups
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Keep at least three copies of your data, including the original and two or more backups.
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Keep your backup data on two different storage types to reduce the chances of failure. If you have data stored on an internal hard drive, make sure you have another copy in a secondary storage type, like magnetic tape.
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Keep at least one backup copy off-site. Local disasters can wipe out multiple copies when both are stored in the same location. Keep a third copy in a secure, offsite location — unplugged. In other words, create an air gap.