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 CBROAM
xx 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.