Call now: 252-767-6166  
Oracle Training Oracle Support Development Oracle Apps

 E-mail Us
 Oracle Articles
New Oracle Articles

 Oracle Training
 Oracle Tips

 Oracle Forum
 Class Catalog

 Remote DBA
 Oracle Tuning
 Emergency 911
 RAC Support
 Apps Support
 Oracle Support

 SQL Tuning

 Oracle UNIX
 Oracle Linux
 Remote s
 Remote plans
 Application Server

 Oracle Forms
 Oracle Portal
 App Upgrades
 SQL Server
 Oracle Concepts
 Software Support

 Remote S


 Consulting Staff
 Consulting Prices
 Help Wanted!


 Oracle Posters
 Oracle Books

 Oracle Scripts

Don Burleson Blog 








ORA-01034: ORACLE Not Available tips

Oracle Error Tips by Burleson

Question:  I am getting the errors ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist.

Answer: The ORA-01034 is  simple error, it means that your database is down!  Oracle oerr utility notes this about the ORA-01034 error:

ORA-01034: ORACLE not available

Cause: Oracle was not started up. Possible causes include the following:

- The SGA requires more space than was allocated for it.

- The operating-system variable pointing to the instance is improperly defined.

Action: Refer to accompanying messages for possible causes and correct the problem mentioned in the other messages. If Oracle has been initialized, then on some operating systems, verify that Oracle was linked correctly. See the platform specific Oracle documentation.

The ORA-01034 error can sometimes be fixed by setting the  ORACLE_SID environment variable:

Unix/Linux :

$export ORACLE_SID
$sqlplus sys/manager@xxx as sysdba

SQL> startup

Window :

C:\> set ORACLE_SID=xxx
C:\> sqlplus sys/manager@xxx as sysdba

C:\> startup

You may find that you are experiencing ORA-01034 when attempting to upgrade your Oracle database. 

ORA-01034 is thrown during the attempt to upgrade because there is an invalid entry in one of the following files:

  1. /etc/oratab
  2. /var/opt/oracle/oratab

The ORA-01034 is a result of a discrepancy between ORACLE_HOME and ORACLE_SID

To resolve ORA-01034, be sure that the ORACLE_HOME and ORACLE_SID properly match within the files /etc/oratab or /var/opt/oracle/oratab .

As a last step in solving your ORA-01034 problem and running DBUA, make sure that  ORACLE_HOME is set to 'old' home, not 'new' home.

This article covers ORA-01034 when trying to change the domain name.  It mentions that:

So long as you have the DNS host name in your tnsnames.ora file, changing the IP address from the DNS file (i.e. /etc/hosts) should not have any changes at the database level.



Burleson is the American Team

Note: This Oracle documentation was created as a support and Oracle training reference for use by our DBA performance tuning consulting professionals.  Feel free to ask questions on our Oracle forum.

Verify experience! Anyone considering using the services of an Oracle support expert should independently investigate their credentials and experience, and not rely on advertisements and self-proclaimed expertise. All legitimate Oracle experts publish their Oracle qualifications.

Errata?  Oracle technology is changing and we strive to update our BC Oracle support information.  If you find an error or have a suggestion for improving our content, we would appreciate your feedback.  Just  e-mail:  

and include the URL for the page.


Burleson Consulting

The Oracle of Database Support

Oracle Performance Tuning

Remote DBA Services


Copyright © 1996 -  2020

All rights reserved by Burleson

Oracle ® is the registered trademark of Oracle Corporation.



Oracle Training at Sea
oracle dba poster

Follow us on Twitter 
Oracle performance tuning software 
Oracle Linux poster