Volume Label Check 
The volume label is always the first file on a volume. This file has a format specific to BRBACKUP/BRARCHIVE and is written to the volume using
cpio
.This label file has the name:
.tape.hdr0
.You can display the contents of a volume label using the call
brbackup|brarchive -i show -n 1
The label includes:- the volume name (for example, tape name)
- Timestamp: when the volume was used for a backup (start timestamp of the corresponding backup with BRBACKUP or BRARCHIVE)
- Name of the database instance (ORACLE_SID)
- BRBACKUP/BRARCHIVE actions ID (coded timestamp of the BRBACKUP/BRARCHIVE log names)
- BRBACKUP/BRARCHIVE function ID (extension of the detail log file name of BRBACKUP/BRARCHIVE)
- Volume use count: how often the volume has been used
Label Check Before a Backup
Before BRBACKUP/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:
- Volume name
An error message (message number BR216X) is issued if you have mounted a volume with an incorrect name. If a scratch volume was requested, you can mount any volume.
- Expiration period
An error message (message number BR217X) 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.
Volume use count
A warning message (message BR235W) is issued if the volume has been overwritten more frequently than specified in the
init<DBSID>.sap
parameter
tape_use_count
.
Label Check After a Backup
After a backup to a volume is completed, the volume label is checked once more. This is to detect volume, volume 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 could be unusable if these systematic errors are not recognized. The system checks whether the name of the database instance, the action ID, and the function ID match the current values.