Managing the Oracle Instance

Stages of database startup and shutdown:

• Startup nomount:
  •  Initialization parameter file is read
• startup open
  •  datafiles and redo log files are read
• startup mount
  •  control files are read

Oracle shutdown options:

• Shutdown normal
• no new connections are allowed

before database is shutdown, the database waits for
all connected users to disconnect recovery is not required on startup

• shutdown immediate
• no new connections are allowed, nor are new transactions allowed to be started after the statement is issuedAny uncommited transactions are rolled back Database rollbacks active transactions and disconnects all users Recovery is not required on startup
• shutdown transactional
• Prevents clients from losing work and at the same  time does not require all users to log off ( no new transactions are allowed, existing transactions are completed and users disconnected after their transactions have completed)no recovery is required
• shutdown abort

Issue this command when
You have problems starting a database instance
When you have to shut down the database instantaneously
No new connections are allowed nor are any new transactions allowed

Current SQL statements are immediately terminated
Uncomitted transactions are not rolled back
Oracle disconnects all the connected users
Recover is required on startup
shutdown timeout
If recovery is required, Oracle starts SMON (system
monitor process) to do the recovery after opening the database.