A computer or smartphone malfunctions, a cyberattack such as ransomware occurs, or a file is accidentally deleted… The risk of losing important data lurks everywhere in our daily lives. In order to avoid regrets when the time comes, we will explain the golden rule for data backup, the “3-2-1 rule” recommended by IT experts around the world.

The 3-2-1 rule is a concise statement of three principles for keeping data safe.

1. Have “3” data (create 2 copies) In addition to the original data, create at least two backup data so that you have three data in total. It spreads the risk so that even if one backup is corrupted, you can recover with the other backup.

2. Save to different types of media Save your backups to different types of media instead of the same type of media (for example, your PC’s internal HDD and another internal HDD). For example, external HDDs and NAS, USB memory and optical drives, etc. This protects data from failures inherent to a particular medium, such as simultaneous equipment failure due to lightning strikes.

3. One of them is stored in a physically separate location (off-site backup) This is the most important and often overlooked point. In the event of a physical disaster such as fire, water, or theft, all of the equipment in your home can be lost. Therefore, one backup is kept in a physically distant location, using cloud storage (Google Drive, Dropbox, etc.) or on a server at your parents’ home or in a remote location.

Nowadays, cloud services have made it easier to implement the 3-2-1 rule. First of all, let’s get into the habit of backing up important photos from your smartphone or PC to two locations: an external HDD and the cloud.