Re: RE : Oracle RAC and external tables

From: Robert Freeman <>
Date: Fri, 18 Dec 2009 13:13:01 -0800 (PST)
Message-ID: <>

I believe that a Shared NFS mount on a SAN might also work as a solution. 

 Robert G. Freeman
Oracle ACE
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From: Bertrand Guillaumin <>
To: "" <>; "" <>
Sent: Fri, December 18, 2009 2:57:34 AM
Subject: RE : Oracle RAC and external tables

What you can do is use a service to always connect to the same node for your uploading batch. 
But then if the node is down, so is the possibility to use the file so you're back to having a spof. Well normally, the node should restart by itself but in case of hardware failure... Now maybe that kind of failure is acceptable for your batch I'm not sure  of your requirements.
Another solution is to push the file on both servers.
Yet another solution is to upgrade ASM to 11GR2(when it's out for AIX), and use acfs(which is a general purpose cluster filesystem). Or use another cluster filsystem. I'm not sure whether OCFS2 is available on AIX or not.

Best regards,
Bertrand Guillaumin
De : [] de la part de Steven Rebello []
Date d'envoi : vendredi 18 décembre 2009 09:54
À :
Objet : Oracle RAC and external tables

Hi list members,

Need your inputs to help understand how RAC and external tables work.

We are planning to use external tables to upload large volumes of data from a flat file, which is FTP'ed into the database server.

Currently, in the DEV environment we have a single-node Oracle instance (non-RAC) which reads the files from the local disk and uploads the data. The upload process is triggered from a web application which calls a PLSQL proc doing the external table creation and loading. Everything works fine.

But now, in the planned production Oracle RAC, since there 2 nodes having separate disks, it is possible that the file is FTP'ed into node 1 but the web application invokes the proc on node 2 due to load balancing. As node2 doesn't have the file on its local disk, the processing fails.

With this background, can you help with the queries below :

- First thought was to place the directory containing the files on the shared SAN, but had been advised against it with the reason that OCFS does not support non-DBF files. Is this a valid point? Couldn't find any reference document for this.
- Planned to use NFS share and point the directory object to that, but then NFS server becomes the single point of failure L Any workarounds for this?
- If we cannot share flat files on RAC, does that mean that RAC and external tables don't gel together?

I've read the documentation and googled this out, but have not been able to get a clear idea of what's the best practice for this situation.

Your inputs/experience/pointers to documentation would be much appreciated.

Oracle 10g Enterprise Edition Release - 64bit - 2 node cluster RAC - AIX 5.3

Steven Rebello

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Received on Fri Dec 18 2009 - 15:13:01 CST

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