Becoming an Oracle DBA

Friends! Let me greet you for having interest in such a wonderful profile of IT, Oracle DBA.

More the Knowledge you have, more the Experience you will gain!

More the Experience you will have, more the Respect you will earn!

Respect will motivate you for great career ahead!!

You might have visited this blog with atleast any of these 10 questions in your mind, Let me guess & answer it one by one for you

  1. Why to become DBA?      

  2. Why to become Oracle DBA?            

  3. Who can become Oracle DBA?

  4. What is Oracle Database?     

  5. How to become Oracle DBA?         

  6. Responsibility of an Oracle DBA?                              

  7.  Life of an Oracle DBA?             

  8. Risks involved?                                    

  9. Advantage?
10. Becoming Master of Oracle DBA?

ORA-17612: Failed to discover Oracle Disk Manager Library, return value 2

DBA’s you must have come across below error post cloning a RAC database to single instance node

RAC database shared server storage must have been managed by third party cluster vendor tools like VERITAS or so

Refer below steps to resolve it 

Issue:

ORA-17612: Failed to discover Oracle Disk Manager Library, return value 2

Solution: 

Improving FTS oracle

This blog is written after resolving sev1 performance issue post DB migration to new setup

Issue: Sql Full table Scan (FTS) Slowness due to change in execution plan post db migration

Background:

Recently we have migrated 11gr2 Single Node prod. DB (ASM/AIX) to 11gr2 RAC 2 node (Linux) using Data Pump, since then started facing the below issue

ORA-01157 ORA-01110 ORA-27037 ASM file Addition Issues

This blog is intended to make DBA’s aware of what havoc it will create if we misplace a command of datafile addition in ASM disk group especially in RAC.

Last night I missed the ‘+’ sign of DG01 while adding a tempfile in new prod RAC DB resulted in below error & file creation in default local/non-shared location of $ORACLE_HOME/dbs

Which is not readable by other instance, being a temp file it had less impact on DB but such incident can happen while adding data DB files which will lead to db outage

My Mistake: 

I missed ‘+’ sign of DG01

SQL>alter tablespace TEMP add tempfile 'DG01' size 20G;

Impact: Any Running session using this file will receive & log error in alert log

SQL> select * from dba_temp_free_space;

ORA-01157: cannot identify/lock data file 1010 - see DBWR trace file

ORA-01110: data file 1010: '/u01/app/ora11g/product/11.2.0/db_1/dbs/DG01'

ORA-27037: unable to obtain file status

Linux-x86_64 Error: 2: No such file or directory

What is Oracle Database ?

An Oracle Database is a Relational Database management System used to store & retrieve the related information.

An Oracle Database server/instance consists of shared memory structure, background processes & storage which handles the functional requirement to manage concurrent & shared data access by users.

Oracle Database product has evolve though its 8i, 9i, 10g & 11g version

Oracle Basic Architecture:

Overview:

Oracle database server is a part of multitier architecture includes Client Machine/Webserver, Middleware Application & Database Server.