How the Browse and Retention Policies Manage the Data Life Cycle

The browse and retention policies that you associate with a client save set control both the growth of the client file index and the media database, and how long data remains available for recovery. Figure 5-4 traces the data life cycle through the client file index and the media database. In the example, the entries for the September 1 through September 7 backup cycle remain in the client index for one month (the browse policy), plus the length of a full backup cycle (one week), to ensure that all dependent entries pass their browse policies. In this case, the file index entries for the September 1 through September 7 backup cycle are removed on October 13. Since the entries exist in the client file index, you can browse and recover the data through the recover program's GUI (nwrecover). As long as the save set's file entries remain in the client file index, the status of the source save sets is browsable. After the save set status changes from browsable to recoverable, you cannot perform file recovery directly.

The status for each save set backed up during the September 1 through September 7 backup cycle remains recoverable until their retention policies expire, plus however long it takes for all the dependent save sets to pass their retention policies. In this case, the entries from the September 1 through September 7 backup cycle change from recoverable to recyclable on December 8. When all of the save set entries on a volume change status to recyclable, the mode of the volume itself changes from either full or appendable to recyclable.

While the status of a save set is either recoverable or recyclable, you can recover any save set from the storage volume by using either the save set recover operation or the scanner program. Alternatively, you can use the scanner program to re-create a save set's entries in the client file index, which enables file recovery directly from the GUI. For more information about using Save Set Recover and the scanner program, see "Save Set Recover and Scanner".

Figure 5-4 Data Life Cycle in the Client Index and the Media Database

On October 13, all data entries from September 1 to September 7 are removed from the client file index. On December 8, the save set entries from September 1 to September 7 in the media database change status from recoverable to recyclable. After all save sets on a volume change status from recoverable to recyclable, the volume mode changes to recyclable. If auto media management is enabled, the volume may be relabeled automatically by Backup to satisfy a volume mount request. After you relabel the volume, all existing data on the volume is unavailable for recovery.

When you relabel a volume for reuse within the same pool, the volume identification (the volume name as it appears on the volume label) remains unchanged. Even so, after relabeling, the information that Backup needs to locate and access all existing data on the volume is destroyed and neither the Save Set Recover feature nor the scanner program are options. At this point, the volume is ready for new data. All existing data is inaccessible and is overwritten.