OAM allows your application to automatically obtain the first or
second backup copy of an object when the primary copy of the object
is in one of the following situations:
- On removable media that is marked not readable (possibly damaged
or destroyed)
- On removable media that is in a library that is offline or pending
offline
- On removable media that is in a library that is not operational
- If a DB2 error is encountered attempting to retrieve the object
data (4 KB or 32 KB table rows) and a backup copy of the object exists,
OAM attempts to retrieve the backup copy of the object to satisfy
the request.
- On removable media that is marked lost or is not-defined
- If a file system error is encountered attempting to retrieve the
object data.
When you activate this function for one or more of the above
conditions, and that condition exists when the OSREQ application interface
retrieves an object, OAM attempts to obtain the first or second backup
copy, if one exists. The backup copy that is selected for retrieval
is determined by the BACKUP1 | BACKUP2 keyword that is specified on
the MODIFY OAM,START,AB command. If this automatic access to backup
objects function is inactive and the primary copy of the object is
not available for any of the above reasons, the OSREQ API passes error
return and reason codes back to the application. If no backup copy
exists and the function is active, the OSREQ API passes error return
and reason codes back to the application. Automatic access to backup
does not automatically force all retrieves to be initiated from backup.
Automatic access to backup copies of objects can be activated and
deactivated by operator commands, or by using access backup keywords
in a SETOPT statement in the CBROAMxx PARMLIB member.
For further information on accessing backup copies, see Starting automatic access to backup copies of objects and SETOPT Statement Syntax: OAM Global Level Parameters.