- To permit restoration of individual files
- To permit wholesale restoration of entire file systems
8.2.1. Different Data: Different Backup Needs
- A backup is nothing more than a snapshot of the data being backed up. It is a reflection of that data at a particular moment in time.
- Data that changes infrequently can be backed up infrequently, while data that changes often must be backed up more frequently.
- Operating System
- This data normally only changes during upgrades, the installation of bug fixes, and any site-specific modifications.
NoteShould you even bother with operating system backups? This is a question that many system administrators have pondered over the years. On the one hand, if the installation process is relatively easy, and if the application of bugfixes and customizations are well documented and easily reproducible, reinstalling the operating system may be a viable option.On the other hand, if there is the least doubt that a fresh installation can completely recreate the original system environment, backing up the operating system is the best choice, even if the backups are performed much less frequently than the backups for production data. Occasional operating system backups also come in handy when only a few system files must be restored (for example, due to accidental file deletion).
- Application Software
- This data changes whenever applications are installed, upgraded, or removed.
- Application Data
- This data changes as frequently as the associated applications are run. Depending on the specific application and your organization, this could mean that changes take place second-by-second or once at the end of each fiscal year.
- User Data
- This data changes according to the usage patterns of your user community. In most organizations, this means that changes take place all the time.