Backup copy

A backup protects your data against unexpected loss. If anything unexpected happens to the original data, you can always recover it from the backup.

Why do you need backups of your data?

In practice, if you have data that is important to you (holiday photos, documents or a database in an application), it is crucial that in the event of a failure of your computer, hard drive or other device on which your files are stored, it is possible to recover them.

Hard drives can be damaged, and computers are increasingly becoming targets of attacks: 

• there are viruses that damage files (e.g. add malicious code to applications). As a result, your applications may, without your knowledge, perform unauthorised operations, such as sending spam to email accounts or performing other operations, such as cryptographic operations
• hacker groups carry out ransomware attacks to encrypt your data and demand payment for decrypting it

There are also much more mundane reasons why creating copies is crucial. Fires or floods can irreparably damage equipment containing valuable data.

Types of backups

There are several basic types of backup:

• Full - copies all selected files (takes up a lot of space, but is the easiest to recover)
• Incremental - copies only files that have changed since the last backup (saves space)
• Differential - copies files that have changed since the last full backup

The 3-2-1 backup rule

The 3-2-1 rule is one of the most important rules of data security. It defines the minimum standard of protection against information loss. In the simplest terms, it boils down to the following elements:

• 3 - Keep at least 3 copies of your data (original + 2 backups)
• 2 - Store copies on two different types of media (e.g. hard drive + cloud)
• 1 - One copy should be stored offsite - in a different physical location or in the cloud.

The 3-2-1 rule protects against various data loss scenarios – if one medium fails, you still have the other copies. If there is a fire or flood in the building, the external copy will remain safe. Different types of media minimise the risk of simultaneous failure for the same reason.

An example of the practical application of the 3-2-1 rule

• Original data on your computer
• First copy on an external hard drive
• Second copy in the cloud (Google Drive, Dropbox, iCloud)

This strategy is widely used by both home users and large corporations as a standard for protecting critical data.