Application VIP and RAC node LISTENER on 0.0.0.0

One interesting thread was started a half year ago on Russian forum SQL.RU.

It is worth to be mentioned here in English.

In general, topic-starter asked about possibility to add additional VIP into cluster configuration to overcome one of consolidation issue – moving database to cluster brings necessarily to modify connection information on many clients machines.

The right way is to use centralized names resolution – like OID,

but topic-starter decided to add to cluster another application VIP with IP-address of server where database was hosted before consolidation.

Nothing unusual, but to be able to made connection to this VIP we need new LISTENER which depends on this VIP and is able to run on any node of the cluster to overcome possible of node down. Once more – nothing unusual, just do job.

What was really interesting in this thread is this post by Alex Roudnev:

“Just modify cluster listeners to listen on address 0.0.0.0 and they will automatically listen on every VIP when it move to another node”

I have checked this configuration in Linux/AIX environment and it really works!

Making proposed recommendations is the easiest way, because You don’t need to make one more additional cluster listener for each database You have to move to cluster.

But there are also some negative aspects which need to be taken into consideration:

  • modifying listeners in this way will, probably (???), make configuration unsupportable, because they designed by Oracle to work in different way
  • You will need to modify LISTENER.ORA files and they will be out of sync with information in OCR
  • listeners will listen on every IP address managed by the server, including IP addressed from public and private and possible some managing networks

Conclusion:

  • modifying listeners to listen on 0.0.0.0 brings quite interesting functionality to the cluster
  • but the RIGHT WAY is:
  • addition of new application VIP hosted on every node of the cluster
  • addition of new LISTENER which depends on that VIP and is able to run on every node of the cluster
  • modify cluster database’s REMOTE_LISTENER parameter to point to added new application VIP
  • set LOCAL_LISTENER to point to local VIP for every instance

Your comments & thoughts are welcome!

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