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Overview

Full Backup Transparency

Classification of Agents based on Index Usage

Overview

The software generates an index of the data, whenever a data protection job is initiated. The index contains a list of all the data objects (files/subdirectories, database objects, mailbox objects, etc.) along with the path to the archive file that stores the data in the media. The index provides quick access to the data in the media during a browse/restore operation.

Each data protection job - whether full, differential, or incremental - creates or accesses an index available in the index cache directory. Whenever a backup is initiated, the system performs the following steps to create/maintain the index:

• Creates either a new index (normally during a full backup) or gains access to a copy of the most recent index version for the subclient.
• Records the changes to the data objects (files/subdirectories, database objects, mailbox objects, etc.) in the subclient along with the path to the archive file that stores the data in the media
• Saves the copy of the index in the index cache directory and also backs up a copy of the index version in the backup media.

During full backups (other than the first one), if full backup transparent browses are enabled, the system also determines the archive files which still exist for the subclient and prunes the index to remove references to file or directory versions which no longer exist. If full backup transparent browses are disabled, a new index is created from scratch upon each full backup, obviating the need to clean up pruned items.

During a browse or restore operation, the system processes the index as follows:

• When the browse operation is initiated, the system returns the list of files requested by the browse by reading the most recent version of the index (associated with the most recent backup). If the most recent version does not contain the necessary information, then the index prior to the most recent is read and so on until all the necessary information is obtained.

  If the index is either not available in the index cache, or not accessible to browse/restore operation then it is restored from the backup media.

• During the restore process the index is used to access the appropriate archive file to the restore data.

Full Backup Transparency

Some Agents support full backup transparency. Full backup transparency provides the facility to browse data within the entire retention period, not just one full backup cycle. In effect, the browse extends back in time, starting with the least recent full backup in the retention period, through the full backups and to the most recent backup. Full backup transparency can be enabled by disabling the generation of new index during a full backup. (By default, full backups are configured to generate a new index.)

Full backup transparent browses depend on how full backups are configured for the Agent. If full backups are configured to generate a new index on each occurrence, then full backup transparent browses are disabled. If full backups are configured to use and build upon the existing index from the previous backup operation (i.e., in the manner of incremental and differential backups), then full backup transparent browses are enabled.

See Full Backup Transparent Browse for additional information.

Classification of Agents based on Index Usage

The following table provides a classification of the various Agents:

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