Backup How-To's: Three Types of Data You May Want to Back Up

In the opening article of the "Backup How-To's" series ("Why Ever Back Up Data?") we discussed the importance of performing regular data backups and estimated the amount of time, money and nerves they save for an average PC user. Now it's time to learn about different approaches to data backup and understand which of them are suitable for which purpose.

Basically, there are three qualitatively different types of information which require different approaches: file backup, image backup and database backup.

File Backup

Backups of files and folders can be easily done manually through the use of ordinary file system queries. Looking very simple on the surface, files-based backup shouldn't be underestimated. It is the most flexible method of backup with multiple strategies and peculiarities. It allows you to back up files of a specific type only, copy only those files and folders that have changed, and much more; also it provides the fastest way to restore data in case of a disaster.

Disk Image Backup

Disk image backup assumes that data is backed up on sector level, regardless of the file system. This type of copying can hardly differentiate sectors with important data and back up only what you need; usually it is used to create a complete snapshot of a hard drive or HDD partition and back it up as a whole. The main advantage of this approach is that it allows backing up operating system, boot records, and all other data that can't be reached through file system requests.

Database Backup

And finally, database backup. Databases consist of "interactive" data that is accessed and modified by many users and programs simultaneously. Often database management systems lock access to certain parts of database tables: for example, when a customer purchases something online, the DBMS locks the respective record until the transaction is finished. Therefore the database becomes unavailable for common copying, and its backup requires more advanced technologies to be used (e.g. special database drivers).

Let's sum up what we've learned so far. There are different approaches to making backups of different types of data. While image-based backup provides complete backup of hard drive contents, file backup is much more flexible and faster. Combining file and image backup appears to be a powerful method for most computers in both the home and business environments. While database backup is less frequent on most workstations, it is a business necessity for servers processing commercial data.

In the next article: Pros and Cons of Backup Software

"Backup How-To's" is a series of articles discussing methods and strategies of organizing computer data protection. These articles will be of great interest and use for PC users of all levels, from those who use computers at home to system administrators in large commercial enterprises.