This parameter defines the maximum size in kilobytes of the backup pieces created by RMAN with an external backup library, that is, backup_dev_type = rman_util|rman_disk|rman_stage.

Syntax: rman_maxpiecesize = <number>

Default: 0 (no limit)

You can also use this parameter to limit the size of a save set created by an RMAN incremental backup to local or remote disk.

This parameter was previously called rman_kbytes.

See also:

RMAN Backup with an External Backup Library

Oracle documentation