Boolean  

Dynamic. Scope = ALTER SYSTEM ... DEFERRED. 

FALSE  

TRUE | FALSE  

BACKUP_TAPE_IO_SLAVES specifies whether I/O server processes ("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. When the value is set to FALSE (the default), Oracle does not use I/O server process for backups. Instead, the shadow process engaged in the backup accesses the tape device.  

Typically, I/O server processes are used to simulate asynchronous I/O on platforms that either do not support asynchronous I/O or implement it inefficiently. However, you can use I/O server processes even when asynchronous I/O is available. In that case, the I/O server processes will use asynchronous I/O. See also "DBWR_IO_SLAVES". 

Only one process can access a tape device at any given time. Therefore, this parameter is Boolean, and allows or disallows deployment of an I/O server process to access a tape device.  

Note: You cannot perform duplexed backups unless you enable this parameter. Otherwise, Oracle returns an error. When this parameter is enabled, Recovery Manager will configure as many server processes as needed for the number of backup copies requested.  

See Also: Oracle8i Recovery Manager User's Guide and Reference for more information on duplexed backups.