Losing data always happens when you least expect it... I hope you have never had the experience of losing data, harddrive failing or memory card crashing. It might be able to retrieve some of the lost files from the failed disk, though prevention will benefit you and will for sure cause less stress. 

Let me introduce you to the 3-2-1 backup rule! 

Keep your data safe with the 3-2-1 backup rule.

What is the 3-2-1 backup rule, and what are the rules?

1. Have at least 3 copies of your data

2. Keep the copies on 2 different media

3. Store 1 copy off site

Pretty easy to follow, here is how it works:

1. Have at least 3 copies of your data
Your original data on your Server, Desktop or Laptop plus an additional two copies of the data. This is to reduce the risk factor of multiple device failures, particularly if some of those are at the same physical location.

One copy is good, but just not good enough if you value your data.

2. Keep the copies on 2 different media
Keeping your backups on the same media as your data is not best practise and increases the risk of looking your data. If you backup on the same RAID array as your production data resides, you are at increased risk of losing data if there is a problem with the array.

The 3-2-1 rule suggests using a mixture of media such as internal drives, external drives, tapes, USB drives, etc.

3. Store 1 copy off site
This means as far away as possible. Another City or County would qualify, keeping your external USB or tape backup in the server room (where it would also get damaged in a fire) or IT managers boot (with increased risk of physical damage) would not qualify.

Backing up to a remote branch office or to the cloud would keep your data safe, even in the event of a local disaster on site.

Keep your data safe!


(source : Cactus IT)