First, look for a server parameter enter the default location. you’ll override the default behavior by using the SPFILE or PFILE parameters within the STARTUP command.
Next, read the parameter file to urge the values of the initialization parameters.
Then, allocate the system global area (SGA) supported the initialization parameter settings.
After that, start the Oracle background processes like SMON, PMON, and LGWR.
Finally, open the alert log and trace files and record all explicit parameters to the alert log within the valid parameter syntax.

At the NOMOUNT stage, Oracle doesn’t associate the database with the instance.

2) MOUNT stage

In the MOUNT stage, Oracle associates a database with an instance. In other words, the instance mounts the database.

The instance carries the subsequent steps to mount a database:

First, get the name of the database control files laid out in the CONTROL_FILE initialization parameter.
Second, open the control files.
Third, find the name of knowledge files and therefore the online redo log files.

When a database is mounted, the database is merely available to database administrators, not all users.

3) OPEN stage

In the OPEN stage, Oracle performs the subsequent actions:

First, open the web data files in tablespaces aside from the undo tablespaces.
Then, select an undo tablespace. The instance uses default undo tablespace if an undo tablespace is laid out in the UNDO_TABLESPACE initialization parameter. Otherwise, it’ll select the primary available undo tablespace.
Finally, open the web redo log files.

When Oracle opens a mounted database, the database is out there for normal operations.

The following picture illustrates the Oracle database startup process:

Oracle STARTUP command

The basic syntax of the STARTUP command is as follows:

STARTUP;

It is like start the database instance within the OPEN stage:

STARTUP OPEN;

If you would like to start out the database instance during a specific stage, you’ll use the subsequent syntax:

STARTUP stage;

For example, to start out up a database instance within the NOMOUNT stage, you employ the subsequent command:

STARTUP NOMOUNT;

To bring the database to subsequent stage, you employ the ALTER DATABASE statement. for instance , this statement brings the database from the NOMOUNT to the MOUNT stage:

ALTER DATABASE MOUNT;

Oracle STARTUP command example

First, launch the SQL*Plus program and log in to the Oracle Database because the SYS user.

Second, issue the SHUTDOWN IMMEDIATE command to pack up the database:

shutdown immediate;

Here is that the output:

Database closed.

Database dismounted.

ORACLE instance pack up .

Third, start the database instance at the OPEN stage:

startup

Here is that the output:

Fourth, pack up the instance again:

shutdown immediate;

Fifth, start the database instance at the MOUNT state:

startup mount;

The output is:

ORACLE instance started.

Total System Global Area 2550136832 bytes

Fixed Size 3835304 bytes

Variable Size 738200152 bytes

Database Buffers 1795162112 bytes

Redo Buffers 12939264 bytes

Sixth, check the present status of the database instance by querying the v$instance view:

SELECT

instance_name,

status

FROM

v$instance;

Output:

INSTANCE_NAME STATUS

—————- ————

orcl MOUNTED

Seventh, bring the database to the OPEN stage by using the ALTER DATABASE command:

ALTER DATABASE OPEN;

Output:

Database altered.

Finally, check the status of the database by executing the subsequent statement:

SELECT

instance_name,

status

FROM

v$instance;

Now, the database is open and available for normal operations.

INSTANCE_NAME STATUS

—————- ————

orcl OPEN

So, this brings us to the end of blog. This Tecklearn ‘How to use the Oracle STARTUP command to start an Oracle Database instance’ blog helps you with commonly asked questions if you are looking out for a job in Oracle DB. If you wish to learn Oracle DB and build a career in Database domain, then check out our interactive, Oracle 12c DBA Training, that comes with 24*7 support to guide you throughout your learning period. Please find the link for course details: https://www.tecklearn.com/course/oracle-12c-dba-course/

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Introduction to Oracle Database

What is the Oracle Database
Pre-requisites for oracle database
Oracle database 12c installation
Multi-tenant architecture

Exploring the Oracle 12c Database Architecture

Explain the Memory Structures
Describe the Process Structures
Overview of Storage Structures

Preparing the Database Environment

Identify the tools for Administering an Oracle Database
Plan an Oracle Database Installation
Install the Oracle Software by using Oracle Universal Installer (OUI)
Create a Database by using the Database Configuration Assistant (DBCA)

Managing the Oracle Instance

Setting database initialization parameters
Describe the stages of database startup and shutdown

Database Storage Structures and Schema Objects

Managing Database Storage Structures
Overview of table space and data files
Overview of Primary Components
Identify the importance of checkpoints, redo log files, and archived log files
Configure ARHIVELOG mode

Database Startup & User Requests and Oracle Network Environment

Describe the stages of database startup and shutdown
Using alert log and trace files
Configure and Manage the Oracle Network
pFile and spFile
Tablespace Management
Storage and Relationship Structure

Oracle Backup & Recovery

Redo log File Management
Performing Database Recovery
Overview of Data Recovery Advisor
Use Data Recovery Advisor to Perform recovery (Control file, Redo log file and Data file)

Deep Dive into Oracle Recovery Manager (RMAN)

Using the RMAN Recovery Catalog
Identify situations that require RMAN recovery catalog
Create and configure a recovery catalog
Synchronize the recovery catalog
Create and Use RMAN stored scripts
Back up the recovery catalog
Create and use a virtual private catalog

Configuring Backup Specifications

Using RMAN to Create Backups
Create image file backups
Create a whole database backup
Enable fast incremental backup
Using RMAN to Perform Recovery
Perform complete recovery from a critical or noncritical data file loss using RMAN
Perform incomplete recovery using RMAN

Data Movement and Oracle Data Pump

Moving Data
Describe and use methods to use move data (Directory objects, SQL* Loader, External tables)
Explain the general architecture of Oracle Data Pump

Data Dictionary & Dynamic Performance Tables

Oracle Data Dictionary contains information related to database privileges
Data dictionary views
Media failure
Flashback CDB

Database Tuning

What is database tuning
How to tune the database
Tuning the data dictionary

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