You are tuning RMAN to optimize performance. You want tape I/O to be asynchronous when
you perform tape backups.
Which action should you take?
A.
Set the BACKUP_TAPE_IO_SLAVES parameter to FALSE.
B.
Set the BACKUP_TAPE_IO_SLAVES parameter to TRUE.
C.
Use compression when performing tape backups.
D.
Configure multiple SBT channels.
B is correct:
https://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmtunin.htm#BRADV89856
Step 2: If You Use Synchronous Disk I/O, Set DBWR_IO_SLAVES
As explained in “Synchronous and Asynchronous Disk I/O”, some operating systems support native asynchronous I/O. If and only if your disk does not support asynchronous I/O, then set DBWR_IO_SLAVES. Any nonzero value for DBWR_IO_SLAVES causes a fixed number of disk I/O slaves to be used for backup and restore, which simulates asynchronous I/O.
To enable disk I/O slaves:
Start SQL*Plus and connect to the target database.
Shut down the database.
Set DBWR_IO_SLAVES initialization parameter to a nonzero value.
Setting DBWR_IO_SLAVES enables the database writer processes to use slaves. Thus, you may need to increase the value of the PROCESSES initialization parameter.
Restart the database.
Restart the RMAN backup.