Recovery refers to the process of restoring and recovering Oracle database files. Normally you will want to perform both restore and recover. However, there may be situations where only one is required.
Select to check datafiles to make sure they exist, are readable, and have the appropriate checkpoint. If any of these conditions is not met, then RMAN restores the files--whether or not they are read-only. By default, RMAN does not restore read-only files when you issue the restore database command.
Specify an identifier in the text box to override the default selection of the most recent backups available. The identifier restricts the automatic selection to backup sets that have the specified identifier. If multiple backup sets have a matching identifier, then RMAN selects the most recent one.
The option is intended for recovery of NOARCHIVELOG databases using incremental backups. In this situation, if you do not specify this option when recovering a NOARCHIVELOG database, Oracle aborts and issues an error.
controls the degree of parallelism within a job. This number specifies the maximum number of connections between RMAN and a database instance. Each connection initiates an Oracle server session on the target instance: this server session performs the work of restoring or recovering backup sets.