Using Single Client Access Name (SCAN) Listeners with Oracle E-Business Suite

[July 30, 2012 update: Corrected Note reference to 823586.1]

[Sept. 2, 2011 update:  Our Maximum Availability Architecture architects have pointed out two additional considerations that are documented in our existing documentation:  1)  Although SCAN listener is supported with EBS 12, if scan_name resolves in DNS to IP1 and IP2, the client-side 10.1.2 network code does not use round robin on the underlyng IPs if the first IP fails.  An Autoconfig solution for this is being tracked through bug 10427234. The only existing workaround is to create custom TNS aliases configured with multiple SCAN IP addresses (Note 823587.1); 2) EBS does support use SCAN functionality, it cannot make complete use of the SCAN since the EBS clients are pre-11.2.  For more details, see this Exadata whitepaper.]

Oracle database 11g logoSingle Client Access Name (SCAN) is a new feature of Oracle Real Applications Clusters (RAC) 11g Release that provides a single name for the clients to access Oracle Database running in a cluster.  The benefit of the SCAN Listener is that the client's connection data does not need to changed if you add or delete a node from a cluster.

The Single Client Access Name is configured during the installation of Oracle Grid Infrastructure. Once configured, application tier connection descriptors just specify the SCAN name rather than all the [virtual] hosts in the cluster.

Without the Single Client Access Name, the descriptor for a two-node cluster would be

VISION =
(DESCRIPTION=
(ADDRESS_LIST=
(ADDRESS=(PROTOCOL=tcp)(HOST=C1-vip)(PORT=1521))
(ADDRESS=(PROTOCOL=tcp)(HOST=C2-vip)(PORT=1521)))
(CONNECT_DATA=(SERVICE_NAME=VISION)))  

With the Single Client Access Name, just the SCAN name needs to be specified:

VISION = (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=C-SCAN)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=VISION)))

The benefit of the Single Client Access Name becomes apparent as the number of nodes in the cluster increases.

Which E-Business Suite releases can be used with SCAN Listeners?

You can configure E-Business Suite Release 11i and 12 environments to take advantage of Single Client Access Name functionality.  The use of SCAN Listener is optional.

EBS 11i

AutoConfig in E-Business Suite 11i does not  support automated handling of SCAN Listeners.  If you would like to use SCAN Listeners with EBS 11i environments, a manual setup process is described in:

EBS 12

AutoConfig in Oracle E-Business Suite Release 12 supports automated handling of SCAN Listeners.  If you would like to use SCAN Listeners with EBS 12 environments, see:

References

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    Comments:

    May be the wrong forum for this, but is this connection string available for use via JDBC? If so, is there an updated Oracle driver?

    Thanks

    Posted by Brent Lowe on September 13, 2011 at 04:01 AM PDT #

    Hi, Brent,

    I don't think anyone following this blog can comment on native use of SCAN listeners with JDBC. You might wish to ask on one of our Oracle RAC forums, or log a formal Service Request with Oracle Support to get an authoritative answer from the database team.

    Regards,
    Steven

    Posted by Steven Chan on September 13, 2011 at 08:56 AM PDT #

    Fair enough, thanks!

    Posted by Brent Lowe on September 13, 2011 at 08:57 AM PDT #

    Hello Steven,

    I just came across a necessity to integrate EBS 11i with the 11GR2 SCAN feature.

    I found the following statement in the "Using Oracle 11g Release 2 Real Application Clusters with Oracle E-Business Suite Release 11i [ID 823586.1]" note:
    AutoConfig does not currently support the SCAN Listener.

    Can I kindly ask to confirm my understanding that SCAN feature isn't supported by AutoConfig in the EBS 11i version and is supported in R12?

    Thank you in advance to your response,

    Yury

    Posted by Yury on February 08, 2012 at 09:37 PM PST #

    -- Please neglect my last comment i submitted. I probably mixed up the screens. I should read this blog post before posting the comment :)
    -- I read the "Using Two New Oracle Database 11gR2 Features With EBS" post first and my intention was to submit the previously comment there. I found the answer under this post.

    Posted by Yury on February 08, 2012 at 09:46 PM PST #

    Hi Steven
    I believe multiple scan listeners are not yet supported by EBS 12.1.3 and we need to make manual jdbc entries. But could it be possible for you to share the oracle doc id , will be really helpful.

    PS: Tried to search on oracle support site but in vain .

    Regards
    Sachin

    Posted by sachin on July 19, 2012 at 12:59 AM PDT #

    Are there any special client requirements for SCAN?

    Or if a client (Windows in particular) works with RAC today, all you need to do is set the TNSnames.ora as mentioned above?

    The syntax looks no different than previous versions.

    Posted by Dan on August 20, 2013 at 02:44 PM PDT #

    Hey Dan,

    The SCAN could be used with most of the Oracle client versions. The only issue is that multiple SCAN IPs are supported starting from 11G version. This way if one of 3 (default) SCAN Listeners listening on 3 IPs are not working, some of your clients will fail to connect to a database.

    Just my .02$

    Posted by Yury on August 20, 2013 at 05:42 PM PDT #

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