Re: Connection String RAC Scan Listener

From: Guillermo Alan Bort <>
Date: Fri, 3 Aug 2012 20:44:02 -0300
Message-ID: <>

  The difference is that if you use the IP addresses instead of the SCAN name you will have to have a more complicated JDBC connect string, but you can add extra control of which server it will hit. This is all of course meaningless with SCAN since it will decide which server your connection needs to go to anyway. With the SCAN name you can also change the physical IPs without need to update configs. SCAN listeners will fail over to active nodes, so as long as you have 1 node, all 3 addresses will hit a live node. The documentation states that you can have up to 3 addresses, but if you have 2 nodes only in the cluster, I recommend using only 2. Of course, if you ever plan to expand the cluster or if you have more than 2 nodes, you should use all 3.

  The benefit of using the SCAN DNS name is that you will automatically know which cluster you are hitting and you won't have to go to a spreadsheet or query the reverse DNS to find out what hostname you are hitting. In an environment with more than one 11.2 RAC, this can be very useful.


On Thu, May 24, 2012 at 4:48 PM, Sanjay Mishra <> wrote:

> Can someone help in explaining as what will be difference in using Scan
> Listener vs its associated 3 IP to the JDBC Thin Driver Connection strings.
> Client Jdbc drivers are 11g R2 Driver.
> What need to understand that Scan Listener Name will be better option or
> 3IP especially from failover perspective if any node Crash and provide more
> reliability.
> Sanjay
> --

Received on Fri Aug 03 2012 - 18:44:02 CDT

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