Thursday, March 4, 2010
starting up an instance in different states
Start the instance without mounting a database. This does not allow access to the database and usually would be done only for database creation or the re-creation of control files. The database instance has been started using initialization file, processes are started and memory is allocated.
alter database mount
Start the instance and mount the database, but leave it closed. This state allows for certain DBA activities, but does not allow general access to the database. The instance is started and the control file is opened, read but it's contents are not validated.
alter database open
startup force restrict
Start the instance, and mount and open the database. Normal database operation means that an instance is started and the database is mounted and open. This mode allows any valid user to connect to the database and perform data access operations. This can be done in unrestricted mode, allowing access to all users, or in restricted mode, allowing access for database administrators only. Normal database operation means that an instance is started and the database is mounted and open. This mode allows any valid user to connect to the database and perform data access operations. If the database is opened then control file is validated against the physical structure of database. The database is verified that all of it's file are in consistent state. If any of the file is not in consistent state, we may need some sort of recovery.
Beginning with Oracle Database 11g Release 2, the preferred (and platform-independent) method of configuring automatic startup of a database is Oracle Restart. Oracle Restart improves the availability of your Oracle database. When you install Oracle Restart, various Oracle components can be automatically restarted after a hardware or software failure or whenever your database host computer restarts.