A database contains hundreds of small datafiles distributed across a high-performance striped storage array. An RMAN backup using a single channel is observing low read throughput. The goal is to increase the number of files read simultaneously by the channel to keep the I/O subsystem busy. The current FILESPERSET is 64. Which action achieves this?

The MAXOPENFILES parameter for an RMAN channel specifies the maximum number of input datafiles that RMAN can read from simultaneously. The default is 8. In a scenario with hundreds of small files on a high-performance I/O subsystem, the default value can lead to I/O bottlenecks as the channel waits for reads to complete. Increasing MAXOPENFILES allows the channel to open and read from more files concurrently, thereby increasing I/O throughput and keeping the storage array busy, which directly addresses the stated goal.

A. RATE is used to throttle (limit) the I/O rate, not increase concurrent file reads. Increasing it would only remove a potential cap, not change the parallelism of reads.
C. SECTION SIZE is used for multisection backups to parallelize the backup of a single large file across multiple channels, not for reading multiple small files by one channel.
D. MAXPIECESIZE limits the size of the output backup piece. Lowering it creates more pieces but does not affect the number of input files read concurrently.

1. Oracle Database Backup and Recovery User's Guide, 23c, "Tuning RMAN Backup Performance". The section on MAXOPENFILES states: "The MAXOPENFILES parameter of the ALLOCATE CHANNEL or CONFIGURE CHANNEL command specifies the maximum number of input files that a backup channel can have open at any given time. The default value is 8."

2. Oracle Database Backup and Recovery Reference, 23c, "CONFIGURE". The description for MAXOPENFILES confirms its purpose is to control the number of concurrently open input files for a channel.