About the set duplex command

RMAN provides an API that lets you make up to four backup sets simultaneously, each an exact duplicate of the others. Using NetBackup, for example, you can back up each copy to a different tape to protect against disaster, media damage, or human error. Use the set duplex and the send commands to take advantage of this feature.

The set duplex command specifies the number of copies of each backup piece to create. The set duplex command affects all channels that are allocated after you issue the command. It remains in effect until explicitly disabled or changed during the session. You cannot issue the set duplex command after allocating a channel.

The command syntax is:

set duplex = {ON | OFF | 1 | 2 | 3 | 4}

By default, duplex is OFF (a single backup set is produced). If you specify ON, it produces two identical backup sets.

Note that you must enable the BACKUP_TAPE_IO_SLAVES initialization parameter to perform duplexed backups. RMAN configures all media as needed for the number of backup copies you request. For more information on BACKUP_TAPE_IO_SLAVES, see your Oracle documentation.

Use the send command to specify the policy and schedule to use with each backup. Because NetBackup uses the policy or schedule to determine what media to use, this information is required for each copy, or an error occurs.

The command syntax is as follows:

send 'keyword=value [, keyword=value,...]';

The keywords that are used to specify a policy are CPF1_POLICY, CPF2_POLICY, CPF3_POLICY, and CPF4_POLICY, which specify the backup policy for duplexed file 1 through duplexed file 4.

The keywords that are used to specify a schedule are CPF1_SCHED, CPF2_SCHED, CPF3_SCHED, and CPF4_SCHED, which specify the Application Backup schedule for duplexed file 1 through duplexed file 4.