Administrator's Reference

DEFINE DBBACKUPTRIGGER (Define the Database Backup Trigger)

Use the DEFINE DBBACKUPTRIGGER command to define settings for the database backup trigger. The database backup trigger determines when ADSM automatically runs a full or incremental backup of the ADSM database and deletes any unnecessary recovery log records.

ADSM uses the settings you specify with this command only when the log mode is set to ROLLFORWARD using the SET LOGMODE command.

With the DEFINE DBBACKUPTRIGGER command, you specify the percentage of the assigned capacity of the recovery log that can be used before ADSM begins a backup of the database. When space usage reaches the percentage you specify, ADSM starts a background process that does the following:

• Runs a backup of the ADSM database using one or more scratch volumes.

  Unless a full backup is required, ADSM runs an incremental backup. A full backup is required when any of the following conditions are true:

  • The database has never been backed up.

  • The database was loaded using a salvage dump created with the DSMSERV DUMPDB command and the database has not been backed up since it was loaded.

  • The maximum number of incremental backups allowed between full backups has been reached.

  • The log mode was changed from NORMAL to ROLLFORWARD.

  • The database was extended or reduced.

  ADSM can continue to write new records to the recovery log while creating a backup of the database.

  Note:

  If a backup initiated by the database backup trigger fails, ADSM waits 60 seconds, and then tries again. It continues to retry the backup until it is successful. If the mount limit for the device class being used for the backup has been reached (all drives busy), ADSM automatically cancels lower priority operations (such as reclamation) to make a mount point available for the database backup. To ensure that a mount point is always available to run a database backup, you can define a device class that is used only by database backup.

• After the backup is successfully completed, ADSM deletes all recovery log records except those required to restore the database to its most current state when used with the backup of the database that was just created.

To display settings for the database backup trigger, use the QUERY DBBACKUPTRIGGER command. To update the settings for the database backup trigger, use the UPDATE DBBACKUPTRIGGER command. To delete the database backup trigger, use the DELETE DBBACKUPTRIGGER command.

Privilege Class

To issue this command, you must have system privilege or unrestricted storage privilege.

Syntax

>>-DEFine DBBackuptrigger---DEVclass--=--devclassname----------->
 
    .-LOGFullpct--=--50-----------.
>---+-----------------------------+----------------------------->
    '-LOGFullpct--=--percentage---'
 
>----+--------------------------------+------------------------->
     '-INCRDEVclass--=--devclassname--'
 
    .-NUMINCremental--=--6--------.
>---+-----------------------------+----------------------------><
    '-NUMINCremental--=--number---'
 

Parameters

DEVclass=devclassname

Specifies the name of the sequential access device class to use for backups. This parameter is required.

If the mount limit for the device class specified has already been reached (all drives are busy) when the backup runs, ADSM automatically cancels lower priority operations, such as reclamation, to make a mount point available for the backup.

Be sure that you have used the DEVCONFIG option in the dsmserv.opt file to specify an external file in which to store a backup copy of device class definitions. If this file is not available and your ADSM database is damaged or lost and must be restored, the definitions created using the DEFINE DEVCLASS command will not be available and must be recreated manually.

You should also use the VOLUMEHISTORY option in the dsmserv.opt file, to specify an external file in which to store a backup copy of sequential volume history information.The volume history file is also used for database recovery.

LOGFullpct=percentage

Specifies when ADSM automatically backs up the database, based on the percentage of available space used for the recovery log. When the percentage of space used for the recovery log exceeds this value, ADSM performs an automatic backup of the database and removes unnecessary records from the recovery log. This parameter is optional. You can specify a value from 1-99. The default value is 50 percent.

INCRDEVclass=devclassname

Specifies the name of the sequential access device class to use for incremental backups. This parameter is optional. If you do not specify a value for this option, all backups are run using the device class specified with the DEVCLASS parameter.

If the mount limit for the device class has been reached (all drives are busy) when the backup runs, ADSM cancels lower priority operations, such as reclamation, to make a mount point available for the backup.

Be sure that you have used the DEVCONFIG option in the dsmserv.opt file to specify an external file in which to store a backup copy of device class definitions. Without the file, if the database is damaged or lost and must be restored, the device class definitions are unavailable and must be recreated manually.

NUMINCremental=number

Specifies the maximum number of incremental backups that can be run before a full backup is required. This parameter is optional. You can specify a value from 0-32. A 0 specifies that ADSM runs only full backups automatically. The default value is 6.

Each incremental backup, whether run automatically by ADSM or run by issuing the BACKUP DB command, is added to the count of incremental backups run.

Each full backup, whether run automatically by ADSM or run by issuing the BACKUP DB command, resets the count for incremental backups to zero.

Note:

If you issue a BACKUP DB command with the TYPE=INCREMENTAL parameter, ADSM performs an incremental backup of the database regardless of the NUMINCREMENTAL setting. For example, you set NUMINCREMENTAL to 5, and there have been five incremental backups since the last full backup. If you then issue BACKUP DB TYPE=INCREMENTAL, an incremental backup is still taken, and the counter for the number of incremental backups since the last full backup is set to 6. This occurs if the BACKUP DB command is issued either by an administrator or through an administrative schedule.

Examples

Task

Define the setting of the database backup trigger at 80 percent. Run two incremental backups to every full backup of the database. Assume a device class of FILE for the backup.

Command:

define dbbackuptrigger devclass=file logfullpct=80 numincremental=2

Related Commands

Table 37. Commands Related to DEFINE DBBACKUPTRIGGER

Command	Description
BACKUP DB	Backs up the ADSM database to sequential access volumes.
DEFINE DEVCLASS	Defines a device class that can be used for storage pools, importing, or exporting.
DELETE DBBACKUPTRIGGER	Deletes the database backup trigger.
QUERY DBBACKUPTRIGGER	Displays information about the database backup trigger.
SET LOGMODE	Sets the mode for saving records in the recovery log.
UPDATE DBBACKUPTRIGGER	Changes one or more attributes of the database backup trigger.