RE: Oracle RAC cost justification?

  • From: "David" <thump@xxxxxxxxxxxxxxxx>
  • To: <niall.litchfield@xxxxxxxxx>, <tim@xxxxxxxxx>
  • Date: Thu, 2 Jun 2005 18:38:18 -0700

SMP machines don't scale in a linear fashion after a certain numbers of
CPU's(Long ago I was told 14).  That is why I was lead to believe
MPP/RAC/OPS/RAC/Grid/Mesh was introduced.

With the right design it made and makes perfect sense.

Alas, Oracle has revamped it and marketed as in a way that makes execs =
wow cheap solution to big expensive SMP machines...well there are holes =
that cheese.

It has it's place...just not many.

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx =
On Behalf Of Niall Litchfield
Sent: Thursday, June 02, 2005 1:40 PM
To: tim@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Oracle RAC cost justification?

Hi Tim
 On 6/2/05, Tim Gorman <tim@xxxxxxxxx> wrote:
> Instead of arguing about whether RAC is good at scalability or HA or=20
> cost-effectiveness, how about citing specifics?
> Q1 - RAC and HA:
> - What does RAC do better than any other possible solution (i.e. OS=20
> clustering, DataGuard, volume replication, etc)? How and why?
> - What other solutions are better than RAC at HA and why?
 I'd argue that any solution that breaks the single location, single=20
database requirement of RAC will give better HA.=20
 Q2 - RAC and scalability:

- When does RAC present a better scalability solution than, say, simply
buying a larger server?
- What scalability bottlenecks does a RAC solution resolve better than
alternatives (i.e. larger server, RAM disk, etc)?
- What other solutions are better than RAC at scalability and why?

Q3 - RAC and cost-effectiveness:

- Compare and contrast the explicit (and implicit) costs to a RAC versus
non-RAC configuration for the following scenarios:

* 8 CPUs of processing capacity required, no HA reqmts stated
* 8 CPUs of processing capacity required, MTTR less than 1 hour
* same as above for 64 CPUS of processing capacity
 I'd link those two. Implicit in your question seems to be the ideas =
 a) you can satisfy your demand with a known number of CPUs
b) you already have that demand.=20
 I see RAC as being a killer app for folk who *right now* need say 2 or =
cpus but may well need 8,16 or 32 as business takes off. If you go the=20
single instance route then what do you do, buy four times as much =
as you currently need just in case? In addition for people who don't =
what their cpu and memory requirements actually are RAC might well make=20
sense. (or they have platform limitations about how much hardware their =
can sensibly address on a given node.) If i'm right the bundling of RAC =

SE in 10g makes a huge amount of sense.=20
 as for cost-effectiveness, as i was trying probably imperfectly to say, =

make sure you are comparing different solutions to the same business=20

Niall Litchfield
Oracle DBA



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