RE: All instances for service are AVAIL none PREF in RAC

From: Mark W. Farnham <>
Date: Tue, 16 Dec 2008 13:04:07 -0500
Message-ID: <>

That is a HUGE it depends.

If you have at least two services that are significantly disjoint in the database objects they use, they you might significantly reduce your total RAC TAX by putting one service as preferred on one instance and the other preferred on the other instance. To the extent that a sincle instances' horsepower can keep up with each service, it may be possible to do the same amount of work with less overhead.

If you have services that are unpredictable in how they overlap in use of database objects over time, then such "APPLICATION AFFINITY" won't buy you much, and you might as well treat your array of nodes "statmux" the way the S.A.M.E. protocol treats the disk farm.



-----Original Message-----

From: [] On Behalf Of Yong Huang
Sent: Tuesday, December 16, 2008 10:46 AM To:
Subject: All instances for service are AVAIL none PREF in RAC

2-node RAC, Redhat 5

I have a service accidentally configured with both instances as available and none as preferred:

$ srvctl config service -d dbname -s PREF: AVAIL: instance1 instance2

Oracle support says there's no harm. Everything will work. Currently the sessions using this service spread on both nodes evenly and seem to work perfectly. Can anybody think of anything I need to be aware of? I intended to configure it as both preferred and none available. Is it worth changing it?

Yong Huang       


-- Received on Tue Dec 16 2008 - 12:04:07 CST

Original text of this message