The 3-2-1 backup rule is a minimum guideline to protect your data. Follow this simple rule and you’ll be well protected to survive when (not if) a problem occurs.
3: Keep 3 Copies of Your Data
This is a minimum. You should have the original files along with two backup copies.
2: Use 2 Different Storage Devices
Your backups need to be separate from your main copy. If you simply copy them to a different folder on the same computer, you’ll likely lose both copies at once. Get an external drive for backup and store it somewhere safe.
1: Have 1 Backup Offsite
Make sure you have a second backup offsite. This can be an automatic cloud backup service. It can also be an external drive stored at a separate location such as your work or home. You want to be sure your data can survive a fire or flood.
This is a minimum. For some files I do even more by mirroring them between multiple computers as well. It’s also important to automate this as much as possible because humans forget to do it. When it’s automated, it’s important to have reports and monitor those reports. It’s easy to set up an automated system, and then forget about it while it silently fails.
If your data is extremely important, it’s sometimes helpful to hire a consultant to manage it for you and provide periodic reports to be sure it’s handled professionally.