OAM records object data on tape volumes using the BSAM OPEN, WRITE,
CHECK, NOTE, POINT, SYNCDEV, and CLOSE macros to process the data
recorded.
If the tape volume is a primary volume that belongs to an Object
storage group and contains the primary copy of the objects, the data
set name of the physical sequential data set is OAM.PRIMARY.DATA. Because the same data set name is created on multiple OAM tape
primary volumes, the data set is not cataloged.
If the tape volume is a backup volume that belongs to an Object
Backup storage group, and it contains the first backup copies of objects,
the data set name of the physical sequential data set is OAM.BACKUP.DATA. If the tape volume is a backup volume that belongs to an Object
Backup storage group, and it contains the second backup copies of
objects, the data set name of the physical sequential data set is OAM.BACKUP2.DATA. Because OAM creates the same data set names
on multiple OAM tape backup volumes, it does not catalog the data
sets.
Attention: - If the DSNWITHSGNAME global keyword is specified on the
SETOAM statement in the CBROAMxx PARMLIB member, the data set names
will have the storage group name appended to the dataset names: OAM.PRIMARY.DATA.sgname,
OAM.BACKUP.DATA.sgname, OAM.BACKUP2.DATA.sgname.
- Allowing the ACS routines to assign or change the data class assignment
of a tape volume is not recommended. The data class for tape volumes
is determined by the SETOAM statement of the CBROAMxx PARMLIB
member at MVS scratch tape allocation. The SETOAM statement provides
this information either at the storage group level or at the OAM global
level and best suits the requirements for the tape volume being allocated.
Allowing the ACS routines to alter this specification could create
unexpected consequences (for example, no compaction of the data when
the SETOAM statement specified compaction). Your installation must
ensure that the ACS routines do not alter the data class construct
for OAM tape volumes.
NOT programming interface information
NOT programming interface information Each user object is recorded as one or more records
within the data set. The maximum number of user object bytes within
a single record is 32 628. No record contains data from more
than one user object. Each record containing object data is self-describing
and starts with a 128-byte prefix. The 128-byte prefix contains the
following information:
- Prefix identifier
- Prefix version number
- Prefix length
- Collection name
- Object name
- Offset of first byte of user data contained in this record
- Length field containing number of bytes of user object data in
this record
- Reserved space
When an OSREQ STORE macro is issued to store an object on tape,
OAM physically writes the object data to the tape media, before the
OSREQ STORE macro returns control to the application program. End of NOT programming interface information
End of NOT programming interface information
Restriction: A single object never spans tape volumes.