Use
The volume expiration period for backups of the Oracle database is defined by the
init<DBSID>.sap parameter expir_period. This specifies the period in days during which a volume is locked, that is, cannot be used. When the period expires, you can reuse the volume for a backup. Volumes are normally tapes, though other backup media are possible.expir_period = 28
means that writing to a volume is possible 28 days after the volume was mounted and used. For example, if you use a volume on Monday 1st July, you cannot use it for another backup until Monday 29th July.The start time of BRBACKUP or BRARCHIVE determines the first day of the lock for all volumes used for a backup. The time when the volume was initialized does not matter. The expiration period always expires at midnight (that is, 00:00 using the 24-hour clock) of the last day of the lock.
SAP recommends an expiration period of 28 days (the default value is 30 days).
If you set an expiration period of 0 days, this means that the volume is not locked. The volumes can be overwritten on the same day. Therefore, do not set
Features
The current value of
expir_period is decisive for whether or not a volume is locked, not the value of the parameter during the backup. This means that the backup volumes are locked for n days after the last backup operation, where n is the current value of expir_period. If the value of expir_period is changed, the expiration period for all volumes is automatically changed.Volumes can be locked physically and logically:
The volume generation date specified on the volume label is decisive for a physical lock. This generation date is determined when the volume label is written (when a backup on this volume was started). A volume is locked physically when the system checks the volume label and finds that the expiration period for the volume has not ended yet, that is, the value of the current date is less than the total of the volume generation date stored in the volume label and the value of
The internal information in the BRARCHIVE or BRBACKUP logs is decisive for a logical lock. The logs are updated when a database file has been backed up successfully. A volume is locked logically when the automatic volume management system checks the volume and finds that the expiration period stored internally has not ended yet; the value of the current date is less than the total of the volume generation date stored in the BRBACKUP or BRARCHIVE logs and the value of
You can unlock volumes as follows:
During a backup, the volume label was written to the volume but the backup was terminated before the first database file could be written to the volume.
This means that the volume is locked physically but not logically. It is selected from the list by the automatic volume management system – with
brbackup|brarchive -i -v <volume name>
When performing this operation, do not use the
A volume was reinitialized before the expiration period ended (for example, with the option
If you still want to use this volume before the logical lock has expired, you can switch off automatic volume management temporarily by mounting the volume on the backup device and entering the following command:
brbackup|brarchive -v SCRATCH
For more information, see: