Re: Not to use SCAN in 11gR2 RAC

  • From: troach@xxxxxxxxx
  • To: yong321@xxxxxxxxx,oracle-l@xxxxxxxxxxxxx,"Robert Freeman" <robertgfreeman@xxxxxxxxx>
  • Date: Sat, 17 Oct 2009 20:16:37 +0000

Instead of thinking of scan as a traditional vip in the oracle grid world, 
think of it as a vip in the F5 sense or the on-demand router in the websphere 
sense. From my understanding it actually forwards requests instead of in the 
rac sense where each machine has a vip and the listener for each machine 
listens to that vip. 
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: Yong Huang <yong321@xxxxxxxxx>
Date: Sat, 17 Oct 2009 12:29:07 
To: <oracle-l@xxxxxxxxxxxxx>; Robert Freeman<robertgfreeman@xxxxxxxxx>
Subject: Re: Not to use SCAN in 11gR2 RAC

Thanks, Robert. But where's the benefit of SCAN to our environment? 
Nobody has provided an answer yet. Everybody's kind response says (1) 
use SCAN because not using it might break future patches, or (2) some 
Oracle employees verbally say SCAN is required, or (3) SCAN is not 

An official statement should not be confused with best practice. The 
former is about breaking something if not followed. The latter is 
about suffering from inconvenience or performance impact if not 
followed. I think the logic is clear here.

Did you have a typo when you say killing CKPT the database still 

Yong Huang

--- On Sat, 10/17/09, Robert Freeman <robertgfreeman@xxxxxxxxx> wrote:

> From: Robert Freeman <robertgfreeman@xxxxxxxxx>
> Subject: Re: Not to use SCAN in 11gR2 RAC
> To: yong321@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
> Date: Saturday, October 17, 2009, 1:53 PM
> I'm not 100% sure that "Official
> Statements" = best practices (in fact I've seen metalink
> notes that make me feel pretty secure that Oracle positions
> on certain things is not quite in alignment with the real
> world). Why must be have an official statement on
> everything? Can't we decide a best practice for ourselves?
> This sounds so much like the small government/big government
> debate we have going on in the states. Do we need Larry to
> tell us every little detail on how to run our databases in
> the form of an "Official statement"?
> It sounds to me like you have gotten quite a bit of
> feedback. As I read that feedback I'm lead to believe that
> it would be best to use SCAN. Based on the responses I see,
> and some experience it would seem that the best practice
> would be to use SCAN. Additionally when Oracle makes it hard
> to NOT use something, it seems to me that there is an
> underlying meaning there which is, basically, use the
> blasted thing. Sure, I can kill CKPT and the database will
> still run (for example) but why bother?
> So the question is, why the resistance? Why are you
> dead-set on NOT using SCAN and looking for the slightest
> justification in the face of what seems to be an
> overwhelming message to use it?
> RF


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