How do I start a DB instance?

Preparing to Start an Instance

1. Start SQL*Plus without connecting to the database by entering: sqlplus /nolog.
2. Connect to Oracle as SYSDBA: connect username/password as sysdba.
3. When you enter a STARTUP command, specify the database name and full path of the parameter file: STARTUP database_name PFILE=myinit.ora.

What happens when Oracle Database startup?

The Open Oracle startup Stage The last startup step for an Oracle database is the open stage. When Oracle opens the database, it accesses all of the datafiles associated with the database. Once it has accessed the database datafiles, Oracle makes sure that all of the database datafiles are consistent.

What is Oracle Database instance?

An Oracle instance (also known as a database instance) contains the set of Oracle Database background processes that operate on the stored data and the shared allocated memory that those processes use to do their work. Each instance has an instance ID, also known as a system ID (SID).

How do I start Oracle Database in Linux?

On Linux with Gnome: In the Applications menu, point to Oracle Database 11g Express Edition, and then select Start Database. On Linux with KDE: Click the icon for the K Menu, point to Oracle Database 11g Express Edition, and then select Start Database.

How do I connect to an Oracle instance?

Connecting to Oracle Database from SQL*Plus

1. If you are on a Windows system, display a Windows command prompt.
2. At the command prompt, type sqlplus and press the key Enter. SQL*Plus starts and prompts you for your user name.
3. Type your user name and press the key Enter.
4. Type your password and press the key Enter.

What is the difference between database and instance in Oracle?

Database Versus Instance The database is the data on disk, stored in operating system files (or possibly, under Unix, in raw files). The instance is composed of the System Global Area (SGA) memory and the background processes. The instance is STARTed using Oracle Server Manager or Oracle Enterprise Manager (OEM).

Which file Oracle will use during startup?

When Oracle starts an instance, it reads the server parameter file (SPFILE) or initialization parameter file to determine the values of initialization parameters. Then, it allocates an SGA, which is a shared area of memory used for database information, and creates background processes.

What is difference between Oracle database and instance?

Oracle Database Instances While the database includes the application data and metadata stored in physical files on a server, an instance is a combination of the software and memory used to access that data. For example, if you sign in to an Oracle database, your login session is an instance.