Enterprise Storage: Four Main Backup Methods

Normal (Full) Backups Full backup is the starting point for backups and is generally the first backup that is made. It involves backing up all of the data in one go.
Incremental Backups Stores files since the last backup that was made.
Differential Backups Backup for all of the changed files since the last full back up.
Mirror Backups Backup the files on to two hard drives in order to ensure that the data is safe and is on two physical devices in order to ensure extra security in addition to being able to ensure that the back ups are not lost over time.