What are the steps involved in Database Startup ?

Showing Answers 1 - 12 of 12 Answers

Vijay Raj Jaiswal

  • Sep 19th, 2005

Three steps are involved

  1. Start an instance.
  2. Mount the database.
  3. Open the database

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sandeep vig

  • Oct 13th, 2005

connect as sys dba and after that give command startup open if u dont want to do any maintenance for the database.otherwise give starup nomount and then alter database mount and finally alter database open

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  • Oct 14th, 2005

start instance, mount the database and open the Database.

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  • Dec 4th, 2005

1. Log in as oracle (or any user in group dba)

2. Set your ORACLE_SID to the instance you want to start. Verify that your ORACLE_HOME is set to the correct database version

3. Start SQL*Plus and connect as sysdba

4. Start the database.

During database startup, you can specify the state it will open to. The default is open(startup), but you can specify STARTUP NOMOUNT or STARTUP MOUNT depending on which task to perform.

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  • Jan 5th, 2006


connect to an ideal instance

now we can start the database with any of the stage as the requirement.






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  • Mar 9th, 2006

Steps are


  • SGA is allocated
  • background processes are started
  • Alert log file is opened

Mount Stage

  • controlfiles is read
  • name & location of the daatfiles, logfiles are detected

Open Stage

  • files are opened

In this way database gets opened. Hope you got clear picture. -- Aruna


  • Mar 19th, 2006

Hi Aruna

Thank you...




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sanjay Pramanaik

  • Aug 24th, 2006

 Hello Aruna,

  The way you have explained the process(steps) involved in database startup is excelent

Best Regards,



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Mohammed Abdul Afroze

  • Mar 26th, 2007


Steps for Database Startup.

(a) Startup Nomount : In Nomount Stage the SGA and Background process gets started.And it will check the database name.

(b)Mount : In Mount stage the Controlfiles,Datafiles and Redolog File will be read at mount stage.

(c)Open : After successfully mount,we can open the Database.

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Chiranjeevi Manne

  • Mar 30th, 2007

NOMOUNT : The init.ora file is read to check the existence of control files.
MOUNT: The control file is read to get check the existence of data files and redolog files
START: The status of various data files is check by comparing the SCN of the file headers of various data files and comparing them with the SCN in control file.

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  • Oct 21st, 2007

There are the three steps need to follow to start database:
1) Start an Instance.
2) Mount the database.
3) Open the database.

Connect with operating system authentication:
conncet / as sysdba
1) Start an Instance:
sql> startup nomount;

2) Mount the database:
sql> alter database mount;

3) open the database:
sql> alter database open;

Every running oracle database is associated with an instance. when a database is started on the database server , oracle allocates a memory area called the system global area(SGA) and start one or more oracle process.
The combination of oracle processes and SGA is called an Oracle instance.

Mount the database:
To mount the database is the process in that instance finds the database control files and open them. In mounting process of database Oracle reads the control files to get the name of the database's datafiles and redo log files.

Open the database:
Opening a mounted database make it available for normal database operation . Any valid user can connect to an open database and access it's information.
Usually a database administrator opens the database to make it available for the general use.
When we open the database, oracle opens the online datafiles and online redolog files

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Steps involved in database startup are as follows

Startup nomount - Instance starts, SGA allocated, Background processes
Used during database creation

Startup mount - Control file read, datafiles & online redolog files are
Used for putting database in archivelog mode & for recovery

Open - All files open database is open for use

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