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 







Oracle tns_admin tips

Oracle Database Tips by Donald BurlesonJanuary 1, 2015

Question: What is the tns_admin parameter and how do I use tns_admin to define a common location for my TNS files?

Answer:  The tns_admin parameter determines the location of the tns administration files (e.g. tnsnames.ora and listener.ora, etc.) 

The tns_admin parameter is super useful on servers with many databases on different release levels (hence different $ORACLE_HOME directories) because all databases tns_admin values can be set to a single location, allowing a single set of SQL*Net files for all databases on the server. 

Without the tns_admin variable, each instance would have it's own set of TNS files in the $ORACLE_HOME/network/admin directory.

Search path steps with tns_admin

The tns_admin defines a list of directories to be searched to find the tnsnames.ora files.  SQL*Net configuration files are resolved in this precedence:

1 - Search for SQL*Net files in present working directory (PWD/CWD)

2 - Set tns_admin for each session or by a user-defined script

3 - Set tns_admin as a global environment variable (in kshrc, cshrc, bashrc, etc.)

4 - tns_admin is defined in the registry (In Windows only)

5 - Search the default location for SQL*Net files in the  $ORACLE_HOME/network/admin directory location (default).

There should be only one tnsnames.ora per server, no matter how many instances reside on it!

Using tns_admin in Windows

In windows, look for the tns_admin registry entry. If  tns_admin is set then you should be able to use a network alias, not the full "(DESCRIPTION..." connect string. The TNS_ADMIN parm tells Oracle clients where to find the tnsnames.ora file.

Also, make sure that  tns_admin is set in your DOS $PATH variable:

C:> set TNS_ADMIN=$PATH;ORACLE_HOME\network\admin

Get the Complete
Oracle SQL Tuning Information 

The landmark book "Advanced Oracle SQL Tuning  The Definitive Reference"  is filled with valuable information on Oracle SQL Tuning. This book includes scripts and tools to hypercharge Oracle 11g performance and you can buy it for 30% off directly from the publisher.



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