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Former Member

RAC on Oracle Shared_Home

We are planning on doing a pilot test for our BI Oracle instances using Oracle RAC 10gR2 on Linux. According to SAP's doc they want you to use a shared oracle_home vs. keeping an oracle_home local per sae each node in the cluster. Why is this? This limits you on minimizing down time and voids the idea of doing rolling patching. The goal is to have more processing power with minimal or no down time.

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3 Answers

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    Former Member
    Feb 20, 2008 at 09:42 AM

    Hi Reynold

    I think it is mainly because of the BRTools. For details have a look at SAP note 905359 - Using BRTools for Oracle RAC databases, point 4 and 5.

    Best regards, Michael

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    Former Member
    Feb 20, 2008 at 03:07 PM

    Thank you for your reply. I have read through that note as well as the BRTOOLS for Oracle RAC databases document. The only restriction stated is that you run brspace or brconnect from one instance, mainly the primary one designated as instance 1. This should be fine w/o having a shared oracle_home as long as you have an oraSID.sap file in the $ORACLE_HOME/dbs directory which can be linked to single common shared file on a globally mounted mount point seen by all the nodes, the same goes for the spfile. Then you just need to have the "/sapmnt" mount point again mounted globally so all nodes can see it. The only restriction that BRTOOLS has that I have seen or encountered problems with is if you don't have your oracle user defined correctly as an OPS$ user in the database which is externally authenticated. So, as long as the OS says yes, you as a valid user on the system and belong to the DBA group, brtools should work fine. You're connecting as "/" anyway which will be the same locally across all nodes. I am missing something?

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    • Former Member

      As i said it is point 4 and 5.

      - brconnect -f cleanup deletes the traces in $ORACLE_HOME/rdbms/audit -> therefore it should be shared

      - if you change init.ora parameters with BR*Tools, you will need one central spfile

      Please don't get me wrong, i am not arguing for or against a shared $ORACLE_HOME. I am sure you can run SAP/RAC with local homes, but it is not supported by SAP at the moment. I just pointed out two minor reasons, although they probably don't bother you that much. Maybe somebody else has some more important SAP reasons for the shared home.

      Personally i think the rolling patch upgrade thing is not really a big issue in 10g, you cannot "roll upgrade" a patchset, and most of the interim fixes. I heard this will be better in 11g.

      Regards, Michael

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    Former Member
    Mar 04, 2008 at 03:56 PM

    It's basically the only way SAP will bless your environment at this time.

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