Re: Two instances, two listeners and /etc/services

Ludo Joris wrote:
> According to Oracle7 Server Installation Guide for HP 9000
> Series 700/800 Release 7.3, Prepare to install SQL*Net version 2
> products, Setup for the Oracle TCP/IP adapter, I added this
> line when installing Oracle7:
>
> listener 1526/tcp #SQL*Net version 2 listener port
>
> From Oracle7 Administrator's Reference for UNIX Release 7.3:
> "Oracle recommends that you reserve a port for your SQL*Net
> listener in the /etc/services file" and "Reserve more than one
> port to start more than one listener".
> So, I should add this line to /etc/services:
>
> listener2 1527/tcp #SQL*Net version 2 listener port
>
> The file /etc/services associates service names and aliases
> with the port number and protocol, says the man page.
>
> I do not understand why exactly I have to add these lines to
> /etc/services.
> What does Oracle mean by 'reserve a port'?
> Do I really need a line in the /etc/services file for every
> instance's listener to make it work?

  It prevents other processes from using the port. Moreover, your clients need to specify the port number in their TNSNAMES.ORA, once the port is used by other processes, they cannot connect to the servers.

---
Name   : Lun Wing San (Certified Oracle Database Administrator)

Title  : Oracle Application Developer of Hong Kong Productivity Council
         Oracle Database Administrator and System Administrator of QRC
Phone  : (852)27885841

This posting represents the personal opinions of the author. It is not the
official opinion or policy of the author's employer. Warranty expired when you
opened this article and I will not be responsible for its contents or use.