Oracle DBA Startup guide Post 2

Oracle Database 10g installation CD is required to do a basic installation. Minimum 4 GB free disk space and 250 MB memory is required to do the installed. It can take at around 30 minutes to install the database. It also does some system checks i.e. utility and file permission.

There are various features in instance configuration

• DBCA ( Database configuration assistance)
• Policy based database configuration
• Initialization Parameter

You can create database both using DBCA or manually from command line.

More in next post....... 

Removing Your Oracle Database

Removing Your Oracle Database
The task of removing an Oracle database differs based on what OS you are running on. For example, if you are running on UNIX, generally you must remove the related database files (database data files, online redo logs, and control files), files in the admin directories related to the database (database parameter files, trace files, etc.), and entries in ancillary database files such as the oratab, tnsnames.ora, and listener.ora files. If you are running on Windows, you need to make the same changes required on UNIX systems, but you also need to remove the database services for the database that you are removing. This will prevent errors from occurring when you start your Oracle database.

You can also use the DBCA to remove a database. The DBCA can be used to drop a database that you created with the DBCA or one that you manually created.

Oracle Database 10g offers a new command, drop database, that takes care of dropping your database for you. You still need to perform ancillary tasks, such as removing the database service and changing database files such as oratab, tnsnames.ora, and listener.ora.

Removing an Oracle database is quite different than removing the Oracle database software. If removing the software is your quest, you should first remove all Oracle databases on your system, and then use the Oracle Universal Installer to remove the Oracle RDBMS software. To completely remove the Oracle RDBMS software, you will probably have to manually remove files from the old ORACLE_HOME, as the installer is not always perfect in its removal process.

Way to create a New database In Oracle

Any person can create a oracle database in two fashion.
1. Using DBCA ( Database Configuration Assistant )
2. Manually

1. Using DBCA: It is a utility provided by oracle and it is present in the $ORACLE_HOME/bin directory. It is a GUI utility and OUI ( Oracle Universal Installer ) installs the software it's normally run this DBCA to create the database.
You can also explicitely run this utility to create database.

2. Manually: You can create database manully using scripts. I am giving an example of creating database using scripts. For this you have to set some veriables.

First run the following command

sqlplus /nolog

Then the following command one after another.

CONNECT SYS AS SYSDBA;
ALTER SYSTEM SET DB_CREATE_FILE_DEST = ‘/user1/oracle/’;
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_1=’ /user2/oracle/’;
ALTER SYSTEM SET DB_CREATE_ONLINE_LOG_DEST_2=’ /user3/oracle/’;


Then run the following command or script

CREATE DATABASE oradba CONTROLFILE REUSE
LOGFILE
GROUP 1 ('/oracle/oradba/log01a.log', '/oracle/oradba/log01b.log') size 50M,
GROUP 2 ('/oracle/oradba/log02a.log', '/oracle/oradba/log02b.log') size 50M,
GROUP 3 ('/oracle/oradba/log03a.log', '/oracle/oradba/log03b.log') size 50M
DATAFILE
'/oracle/oradba/system.dbf' 250M
AUTOEXTEND ON MAXSIZE 500M
UNDO TABLESPACE undots
DATAFILE '/oracle/oradba/undots.dbf' 50M
DEFAULT TEMPORARY TABLESPACE temp
TEMPFILE '/oracle/oradba/temp.dbf' size 75M
EXTENT MANAGEMENT LOCAL
CHARACTER SET US7ASCII
MAXLOGFILES 10
MAXLOGMEMBERS 10
MAXLOGHISTORY 1
MAXDATAFILES 500;

The database named oradba will be created.