Backup

Selecting Backup Type

There are several factors to consider when deciding what backup to use, including the following issues:

The normal backup type is best when a large amount of data changes between backups or to provide a baseline for the other backup types.
The incremental backup type is best to record the progression of frequently changed data.
The differential backup type simplifies the process for restoring files.
To provide for long-term storage with fewer media, you can use a combination of a normal backup plus either incremental or differential backups.

Some backup types use backup markers, also known as archive attributes, to track when a file has been backed up. When the file changes, Windows 2000 marks the file to be backed up again. Files or directories that have been moved to a new location are not marked for backup. Backup allows you to choose to back up only files with this marker set, and you can choose whether or not to mark files as having been backed up.

Table 12.3 lists the main advantages and disadvantages associated with common types of backup.

Table 12.3 Advantages and Disadvantages of Backup Types

Backup type	Advantages	Disadvantages
Normal	Files are easy to find because they are always on a current backup of your system or on one medium. File recovery requires only one medium or set of media.	Most time-consuming. If files do not change frequently, backups are redundant.
Incremental	Least data storage space required. Least time-consuming.	Files can be difficult to find, because they can be on several media.
Differential	Recovery requires only the last normal backup medium and last differential medium. Less time-consuming than normal backups.	Recovery takes longer than if files were on a single medium. If large amounts of data change daily, backups can consume more time than incremental backups.