Explanation:
RMAN can use I/O slaves only if the operating system supports asynchronous I/O. The large pool is a new area in the Oracle SGA that supports the Recovery Manager tool in recovering the Oracle database. This memory are is optional, and when it is configured, it will improve RMAN performance by offering buffer space in memory for I/O slave processes to use when backing up the database or restoring file components from tape.
Incorrect Answers:
1: I/O slaves can be enabled if operation system supports asynchronous I/O, it is not related with size of shared pool.
3: There is no USE_IO/SLAVES parameter in Oracle.
4: Setting BACKUP_TAPE_IO_SLAVES to TRUE will not enable a dedicated slave to write to a tape device.
Multiple I/O slave process are used when BACKUP_TAPE_IO_SLAVES is set to TRUE and when BACKUP_DISK_IO_SLAVES is greater than 0.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 567
Chapter 12: Overview of Backup and Recovery

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