Re: 10g with HACMP (no RAC)?

From: DA Morgan <>
Date: Wed, 10 Sep 2008 07:33:37 -0700
Message-ID: <> wrote:
> On Wed, 10 Sep 2008 01:45:35 +0100, Palooka <>
> wrote:

>> facilities; it is limited in that the vendor does not support RAC, 
>> except in an active/passive configuration, and the vendor has openly 
>> stated that without major code changes, it will not scale at all with RAC.
>> Thus the issue at hand is resilience, rather than scaleability. Agreed 
>> that RAC or DataGuard could offer transparent failover, but the 
>> application itself is another component of the stack, and requires a 
>> minute or two downtime in the event of failure.

> Again, RAC is transparent to an application. RAC itself will not make
> an application unscalable. If it is unscalable using RAC, it likely
> doesn't scale as a normal app either.

Technically true but not necessarily the full story.

RAC has what Oracle internally refers to as the spotlight effect. While it is true that what is poorly written won't scale. And that what is poorly written won't scale well in a stand-alone environment. It is also true that RAC has a way of shining a very bright light on unscalable code. It will fall over far faster on a RAC cluster than stand-alone. That being, to a great degree, related to the sharing of blocks, locks, and sequences across the cache fusion memory interconnect.

What Palooka's vendor is saying is that they are selling a pile of rubbish and that rather than fixing it they want their customers to only install it in a configuration that covers up for their errors in architecture and coding. They lose a few wise customers but keep most people limping along.

If I found a vendor that said what Palooka's vendor has apparently said I would be interviewing other companies and examining competitive products.

What I can not understand, given that HACMP does not truly compete with RAC but rather with Data Guard is why this discussion continues to be about RAC.

Daniel A. Morgan
Oracle Ace Director & Instructor
University of Washington (replace x with u to respond)
Puget Sound Oracle Users Group
Received on Wed Sep 10 2008 - 09:33:37 CDT

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