The backup methods used by Backup Exec are as follows:

• Full. Includes all of the data that was selected for backup and uses the full backup method. Backup Exec detects the device as having been backed up. You can use either archive bit or modified time to determine if a file has been backed up.

  Note:

  You will need to perform a full backup of your server to establish a baseline for disaster recovery.

  Full backups also include Copy backups, which include all selected data and do not affect any media rotation scheme because the archive bit is not reset. Copy backups are useful when you need to:

  • Back up data for a special purpose (for example, to send to another site).

  • Back up specific data.

  • Perform an additional backup to take off-site.

  • Back up data that belongs to a media rotation job without affecting the rotation cycle.

  Another Full backup option is the archive backup option, which automatically deletes files from the volume after they have been successfully backed up. This backup method is designed for migrating data from disk to storage media and should not be incorporated in a regular backup schedule.

  Using the archive backup method allows you to free valuable disk space and reduce clutter on your server volume by migrating stagnant directories and files from the server to media. An archive backup job backs up the selected data, verifies the media, and then deletes the data from the volume.

  Note:

  For data to be deleted, rights to delete a file must be granted; otherwise data will be backed up but not deleted. Backup Exec will not delete data from Backup Exec Agent workstations when using the archive feature.

• Differential. Includes all files that have changed since the last full or incremental backup. The difference between differential and incremental backups is that incremental backups include only the files that have changed since the last full or incremental backup.

  Backup Exec provides two differential backup methods, one that uses archive bit and one that uses modified time to determine if the file was backed up. If you select to use the Full - Back up files - Using archive bit (reset archive bit) and want to run differential backups, you must use the Differential - Back up changed files since last full - Using archive bit (does not reset archive bit) method. If you select to use the Full - Back up files - Using modified time, you must use the Differential - Back up changed files since last full - Using modified time method.

  Note:

  If you use modified time to determine if files have been backed up, the full and differential backups must use the same backup selection list.

  In most schemes, differential backups are recommended over incremental backups. Differential backups allow much easier restoration of an entire device than incremental backups since only two backups are required. Fewer required media also decreases the risk of not being able to restore important data because of media errors.

  You should not mix differential and incremental backups together.

• Incremental. Incremental backups include only the files that have changed since the last full or incremental backup.

  Backup Exec provides two incremental backup methods, one that uses archive bit and one that uses modified time to determine if the file was backed up. If you select to use the Full - Back up files - Using archive bit (reset archive bit) and want to run incremental backups, you must use the Incremental - Back up changed files since last full or incremental- Using archive bit (reset archive bit) method. If you select to use the Full - Back up files - Using modified time, you must use the Incremental - Back up changed files since last full or incremental - Using modified time method. The advantages and disadvantages described in this section pertain to either type of differential backup.

  Note:

  If you use modified time to determine if files have been backed up, the full and incremental backups must use the same backup selection list.

• Working set. The working set backup option includes two options; Changed today and Last accessed in x days. The Changed today option was called Daily backup in previous versions of Backup Exec. You can perform backups using the Changed today method in addition to the media rotation scheme selected. The Changed today method backs up all files with today's date (created or changed today). The Changed today method does not affect the files' backup status because the archive bit is not reset.

  If you select the Last accessed in x days method, you can then indicate in the Files accessed in x days field that you want to include data that has been accessed in a specific number of days.

  This option is similar to a differential backup, in which files that have been created or changed since the last full backup are included; however, the difference lies in that you can also specify to include all files accessed within the last x number of days. This option can speed the recovery of a crashed server because you only need to restore the working set backup to get up and running again, and then restore the latest full backup at a later time (if necessary).

  To effectively include the data needed to make your system operational after restoring a working set backup, specifying at least 30 days in the Files accessed in x days field is recommended. With a full/working set backup scheme, the non-full backups will require more media space than full/differential or full/incremental schemes. However, in environments where active data is migrated frequently between machines, or when restore times are especially critical, working set backups can make up the cost of extra media in time savings for restoring data.