Configuring database backup stacking on tape

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Configure database backup stacking on tape to store multiple full database backups sequentially on the same tape volume, improve tape utilization, and reduce tape media consumption.

About this task

Database backup stacking helps reduce tape media usage, improve tape capacity utilization, and minimize the number of scratch volumes required for database backup operations. Database backup stacking is supported only for eligible tape device classes, such as LTO-8 and later, and supports single-stream full database backups.

By default, each database backup operation uses a new scratch tape volume. When database backup stacking is enabled, the server reuses eligible tape volumes and appends subsequent backups to the same tape until the volume reaches capacity or the configured backup limit.

The server maintains a dedicated backup volume group for each enrolled tape device class. During a backup operation, the server selects a reusable volume from the group by using a round-robin selection method. If no eligible volume exists, the server automatically adds a new scratch volume to the group.

The server tracks the tape write location for each backup and stores the information in the volume history file. During restore operations, the server uses the recorded tape position to locate the correct database backup.

Database backup stacking is enabled only for the tape device classes that are specified in the DBBKPSTACKINGDEVCLASSLIST option.

Before you begin

Before you configure database backup stacking, ensure that your environment meets the following requirements:

  • Use supported tape device classes, such as LTO-8 or later.
  • Configure database backups to use single-stream operations (NUMSTREAMS=1).
Restriction:

The following restrictions apply when database backup stacking is enabled:

  • Only full database backups are supported.
  • Incremental and snapshot database backups are not supported.
  • Multi-stream database backups are not supported.
  • The VOLUMENAMES parameter cannot be specified in the BACKUP DB command.
  • The feature is supported only for tape device classes.

Procedure

Enable database backup stacking

  1. Enable the database backup stacking feature. 
    SETOPT DBBKPSTACKING 1
    Values:
    0: Disables database backup stacking. This value is the default.
    1: Enables database backup stacking.
  2. Specify the tape device classes that must participate in database backup stacking. 
    SETOPT DBBKPSTACKINGDEVCLASSLIST devclass1,devclass2

    Replace devclass1,devclass2 with a comma-separated list of tape device classes.

    Example:

    SETOPT DBBKPSTACKINGDEVCLASSLIST LTOCLASS1,LTOCLASS2
    Note:
    • Only the specified device classes use backup stacking.
    • The server validates the specified device classes before enrollment.
    • Configuration information is stored in the database.
    • To disable stacking for all device classes, clear the list or disable the DBBKPSTACKING option.
  3. Configure the number of tape volumes that the server maintains in each backup volume group. 
    SETOPT DBBKPSTACKINGVOLCOUNT volume_count

    Replace volume_count with the number of tape volumes.

    Values:
    Default: 2
    Range: 2 to 5
  4. Configure the maximum number of backups that can be stored on a single tape volume. 
    SETOPT DBBKPMAXBKPCOUNT backup_count

    Replace backup_count with the maximum number of backups per tape volume.

    Values:
    Default: 5
    Range: 2 to 10

    When the maximum backup count is reached, the server removes the tape volume from the active backup volume group. The volume remains available for restore operations.

Verify the configuration

  1. Issue the following commands to verify the configuration: 
    QUERY OPTION DBBKPSTACKING
QUERY OPTION DBBKPSTACKINGDEVCLASSLIST
QUERY OPTION DBBKPSTACKINGVOLCOUNT
QUERY OPTION DBBKPMAXBKPCOUNT

    The DBBKPSTACKINGDEVCLASSLIST option displays the device classes that are enrolled in database backup stacking.

Modify enrolled device classes

  1. To add device classes to the stacking configuration, specify the updated device class list. 
    SETOPT DBBKPSTACKINGDEVCLASSLIST LTOCLASS1,LTOCLASS2,LTOCLASS3
  2. To remove a device class, omit the device class from the list. 
    SETOPT DBBKPSTACKINGDEVCLASSLIST LTOCLASS1,LTOCLASS3

Disable database backup stacking

  1. To disable database backup stacking, run the following command. 
    SETOPT DBBKPSTACKING 0
    Note:

    When a device class is removed from the configuration:

    • The server removes the associated configuration from the database tables.
    • Existing backup volumes remain available for restore operations.
    • Future backups use standard non-stacking behavior.

Results

After database backup stacking is configured:

  • The server automatically manages backup volume groups for enrolled tape device classes.
  • Multiple database backups are written sequentially to the same tape volume.
  • Tape utilization improves because partially used tapes are reused.
  • Backup history records include the tape start and end positions for each backup.
  • Tape volumes are removed from the active rotation group after the configured backup limit is reached.

What to do next

After you configure database backup stacking:

  • Monitor backup operations and tape utilization.
  • Review the activity log and volume history information regularly.
  • Adjust volume group and backup count settings based on tape capacity and backup frequency.
  • Periodically reclaim expired tape volumes according to your retention policy. For more information, see Reclamation of database backup tape volumes.