This topic discusses the *BACKUP volume type and the unique backup process that are associated with a *BACKUP volume.
Using Copy Optical (CPYOPT) to a *BACKUP volume is no longer the suggested way of backing up your volumes because of the time required. Duplicate Optical (DUPOPT) is the recommended way of backing up your volumes.
The *BACKUP volume type supports the backing up and protection of information from optical *PRIMARY volumes. The system does not allow user programs or APIs to write to optical *BACKUP volumes. Only a limited set of optical commands can update *BACKUP volumes. Once the system creates a directory or file on an optical *BACKUP volume, the only way to delete them is to reinitialize the volume. Doing this prevents either accidental or intentional deletion.
Backup volumes and directories contain a Complete Backup Range file which contains date information about prior copy requests to the optical *BACKUP volume. These dates are helpful in determining the contents of backup directories and volumes with respect to the contents of their primary counterparts. These control dates make it easier to recover by providing a time checkpoint. Each backup directory has its own control dates. Each backup volume also has its own control dates, which include:
The system writes these dates to the backup volumes in a reserved file within each backup directory. Since the system writes the dates to the media, the backup volumes are self-contained. Not only is the backup data on the media, but the recovery information is there as well.