Determining which media to use for backup copies

OSMC uses the AUTO BACKUP parameter on the management class to determine if backup copies of an object should be written. OSMC schedules writes of two backup copies if all of the following items are true:

The AUTO BACKUP parameter equals Y.
The number of backup versions that is specified in the management class field, NUMBER OF BACKUP VERSIONS (DATA SET EXISTS), is greater than or equal to two (≥2).
A SECONDBACKUPGROUP keyword is specified in a SETOSMC statement in the CBROAMxx PARMLIB member.

The backup copies of the object are written to the Object Backup storage groups assigned to the Object storage group to which the object belongs. Using the SETOAM statements, you can specify that the backup copies of the object be written to the same removable media type or to different removable media types, or both. The media that is selected for the backup copies might be optical or tape. If OAM is initialized with a CBROAMxx PARMLIB member containing SETOAM statements for the Object Backup storage groups, and the SETOAM statements include valid TAPEUNITNAME specifications, the backup copies are written onto tape media. If the TAPEUNITNAME is not valid, OAM initialization fails. If no valid SETOAM statements exist for a given Object Backup storage group, all backup copies written to that Object Backup storage group are written to optical media.

Note: If the Management Class associated with the object has AUTO BACKUP = Y and BACKUP FREQUENCY = 0, then the first backup copy is created at the time the object is initially stored.

OSMC schedules a write of only one backup copy if all of the following items are true:

The AUTO BACKUP parameter equals Y.
The NUMBER OF BACKUP VERSIONS (DATA SET EXISTS) parameter is less than two.

OAM writes the single backup copy to the designated Object Backup storage group onto the media type that is assigned for that storage group.

Tip: The default number of backup versions in the NUMBER OF BACKUP VERSIONS (DATA SET EXISTS) field is two.

Note: If the Management Class associated with the object has AUTO BACKUP = Y and BACKUP FREQUENCY = 1, then the first backup copy is deferred to the first OSMC Storage Group cycle after the object was initially stored.

First and second backup copies of objects can never reside on the same tape volume or optical disk volume. The primary copy is stored on a volume belonging to the Object storage group. The first backup resides on a separate volume belonging to the Object Backup storage group designated as the first object backup storage group, and the second backup resides on a separate volume belonging to the Object Backup storage group designated as the second object backup storage group. A single tape volume or optical disk cannot belong to more than one Object or Object Backup storage group. The first and second backup copies of objects belong to separate Object Backup storage groups, therefore cannot reside on the same volume.

The optical disk volume that is chosen to store the primary copy or first or second backup copies of the object is an optical volume (primary copy) or backup optical volume (backup copy) that is contained in one of the real or pseudo optical disk libraries that are listed in the Object or Object Backup storage group definitions.