How Database Is Mounted

The Instance mounts a database to associate the database with that instance.To mount the database.the instance finds the database control files and opens them.Control files are specified in the CONTROL_FILES initialization parameter in the parameter file used to start the instance.Oracle then reads the control files to get the names of the database's data files and redo log files.At this point, the database is still closed and is accessible only to database administrator. The database administrator can keep the database closed while completing specific maintenance operations. However , the database is not yet available for normal operations.

How a Clone Database Is Mounted

A clone database is a specialized copy of a database that can be used for tablespace point-in-time recovery . When you perform tablespace point-in-time recovery. you mount the clone database and recover the tablespace to the desired time. then export meta data from the clone to the primary database and copy the data files from the recovered tablespaces.