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Enable Async IO to Tape

Notes:

This example shows how to enable asynchronous I/O to tape device(s). This is accomplished with the BACKUP_TAPE_IO_SLAVES parameter. The Oracle9i Database Reference says this about this parameter: “BACKUP_TAPE_IO_SLAVES specifies whether I/O server processes (also called slaves) are used by the Recovery Manager to back up, copy, or restore data to tape. When the value is set to true, Oracle uses an I/O server process to write to or read from a tape device.”
The BACKUP_TAPE_IO_SLAVES parameter cannot be changed for the current instance. You must restart the database to put the change into effect.
Note that it is also important to allocate memory to the large pool for the tape buffers; otherwise the memory is taken from the shared pool, which can cause unnecessary contention in for shared pool resources. Chapter 14 of the Oracle9i Recovery Manager User’s Guide contains this formula for calculating the space required in the shared pool for tape buffers:
RMAN large pool requirement* =
number_of_allocated_channels * (16 MB + ( 4 * size_of_tape_buffer ) )
* Add the result of this calculation to your existing large pool allocation.