This "rule" is credited to photographer Peter Krogh and it is both simple and thorough.  You will have to decide if you want this for your project, but we certainly recommend giving it a moment or two of your thoughtful consideration.

1. Have at least three (3) copies of your data

By three copies, I mean that in addition to your primary data, you should also have at least two more backups. Why isn’t one backup enough? It would be all of your digital "eggs" in one "basket" storage container.  Considering your monetary and emotional investment, do you really want all of that risk concentrated in one place? 

This is why having more copies of your data means you will have less risk of losing data during a disaster.  In short, if your data is truly important to you, be sure to make at least two backup copies.

Note: Another reason to create more than two copies of data is to avoid the situation when the primary copy and its backup are stored in the same physical location.

2. Store the copies on two (2) different media

The 3-2-1 rule suggests that you keep copies of your data on at least two different storage types, such as external optical storage discs AND internal hard disk drives or other removable storage media types (e.g., tapes, external hard drives, USB drives, SD-cards, etc) in different storage locations.

3. Keep one (1) backup copy offsite

Physical separation between copies is important. It’s really not a good idea to keep all copies in the same room or in the same location.  If there was a fire or flood, even having multiple copies you could still suffer a total loss of all of your data.

Many people find it feasible to give full copies to other family members who live elsewhere, or place them in a fireproof safe box, or even a bank safety deposit box.  Whatever method you decide upon, know that we are here to help make those objectives obtainable.  We might even have a few suggestions for you, based upon our experience.