Introduction to Database Startup and Shutdown

An Oracle database may not always be available to all users. To open or close a database, or to start up or shut down an instance, you must be connected as SYSOPER or SYSDBA. Normal users do not have control over the current status of an Oracle database.

Database Startup

Starting a database involves three steps:

1. Starting an instance

   An instance controls the background processes and the allocation of memory area to access an Oracle database.

2. Mounting the database

   Mounting the database associates it with a previously started instance.

3. Opening the database

   Opening the database makes it available for normal database operations.

For more information about database STARTUP, see the Oracle8i Concepts manual. For information about the STARTUP command, see the "Command Reference" in Chapter 8.

Example 5-1 Starting an Instance

To start an Oracle instance, without mounting the database, enter

SQL> STARTUP NOMOUNT

Example 5-2 Mounting the Database

To start an instance, mount the database, but leave the database closed, enter

SQL> STARTUP MOUNT

Example 5-3 Opening the Database

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

SQL> STARTUP OPEN sales PFILE=INITSALE.ORA EXCLUSIVE RESTRICT

Database Shutdown

Shutting down a database involves three steps:

1. Closing the database

   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.

2. Dismounting the database

   Dismounting the database disassociates the database from an instance and closes the control files of the database.

3. Shutting down the instance

   Shutting down an instance reclaims the SGA from memory and terminates the background Oracle processes that constitute an Oracle instance.

For more information about database SHUTDOWN, see the Oracle8i Concepts manual. For information about the SHUTDOWN command, see the "Command Reference" in Chapter 8.

Example 5-4 Shutting Down the Database

To shut down the database in normal mode once it has been opened and mounted, enter

SQL> SHUTDOWN
Database closed.
Database dismounted.
ORACLE instance shut down.