|SQL*Plus User's Guide and Reference
Database Administration, 3 of 5
An instance controls the background processes and the allocation of memory area to access an Oracle database.
Mounting the database associates it with a previously started instance.
Opening the database makes it available for normal database operations.
To start an Oracle instance, without mounting the database, enter
To start an instance, mount the database, but leave the database closed, enter
To start an instance using the parameter file INITSALE.ORA, mount and open the database named SALES in exclusive mode, and restrict access to administrative personnel, enter
Shutting down a database involves three steps:
When a database is closed, all database and recovery data in the SGA are written to the datafiles and redo log files, and closes all online datafiles.
Dismounting the database disassociates the database from an instance and closes the control files of the database.
Shutting down an instance reclaims the SGA from memory and terminates the background Oracle processes that constitute an Oracle instance.
To shut down the database in normal mode once it has been opened and mounted, enter