There are a variety of ways to backup data and many variations of the basic methods. These are some major types of backups:
An image backup backups-up everything on a hard drive including system files, boot sectors, system files, hidden files, applications, data files, etc. An image backup is useful for restoring a hard drive after a catastrophic failure. Such failures can include hard drive failures or severe software or virus problems. The system will be restored with the exact image of the hard drive at the time of the backup. Any changes after that backup will be lost. Only perform an image backup if you are sure that the hard drive is free from malware and viruses.
- Advantage: Can restore the same computer after hard drive or Operating System failure.
- Disadvantage: Problems on the hard drives, such as viruses, are replicated on the image.
- Disadvantage: Requires an application to backup and restore the image.
- Disadvantage: Will probably NOT work if switching computers.
In a full backup all files are copied to the backup device. The files can either be copied as is or compressed. Copying the files uncompressed takes the most time and space but the files can be accessed directly.
- Advantage: Files can be backed-up without any special backup software.
- Advantage: Very versatile and all files are directly accessible.
- Disadvantage: Backup take more time and space.
With an incremental backup starts with a full backup. On the next backup the files in the previous backup are compared with the current files to backup. The backup contains the files that were added or changed since the last backup. Incremental backups are faster to run and take less space than a full backup. When restoring files the system must decipher which version of the files are the latest since there could be multiple versions of the file in the archive.
- Advantage: Takes less time and space then full backup.
- Disadvantage: Requires application to manage backups.
- Disadvantage: Single backup of file set (excluding old version of files).
A rotating backup uses multiple full backups stored by date. Keep 3-5 multiple full backups. If you have more than your desired number of backups delete the oldest and do a full backup. You will have multiple backups of all files in case a file is lost or compromised. You will also mirror the backup drive in case the backup hard drive fails.
- Advantage: Takes lots of space.
- Advantage: Multiple copies of files and they are easy to access.
- Disadvantage: Requires the most time and space.
I use multiple USB hard drives and create rotating full backups. One backup is kept on-site and one off-site. Storage is small and inexpensive so I prefer the ease and versatility of having multiple full backups. I keep three sets of dated backups per drive.