Accessing backup objects automatically

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.