You must first initialize tape volumes before you can use them to back up your Oracle database with BRBACKUP or BRARCHIVE. When BRBACKUP or BRARCHIVE writes to a volume, it first checks the volume label. The following graphic shows the volume label and check:
You can display the contents of a volume label as follows:
brbackup|brarchive -i show -n 1
The volume label is always the first file on a volume. This file has a format specific to BRBACKUP or BRARCHIVE and is written to the volume using cpio. The label file is called .tape.hdr0.
BRBACKUP or BRARCHIVE performs the following volume label checks:
1. Before BRBACKUP or BRARCHIVE writes to a volume, it reads the volume label file. If this file does not exist, you have to either initialize the volume or mount another volume.
The following volume label information is checked:
Ў Volume name
An error message (message number BR0216E) is issued if you have mounted a volume with an incorrect name. If a scratch volume was requested, you can mount any volume.
Ў Expiration period
An error message (message number BR0217E) is issued if the configured expiration period – number of the days specified in the init<DBSID>.sap parameter expir_period that must have passed before the volume can be used again – has not ended yet.
Ў Volume use count
A warning message (message BR0235W) is issued if the volume has been overwritten more frequently than specified in the init<DBSID>.sap parameter tape_use_count.
2. After a backup or archive to a volume is completed, the volume label is checked once more. This is to detect volume, tape device, driver, or hardware errors that would prevent a successful backup, but would not cause an error message to be issued. In extreme cases, several sequential backups might be unusable if these errors are not recognized. The program checks whether the name of the database instance, the action ID, and the function ID match the current values.