Re: Oracle RAC cost justification?

  • From: Niall Litchfield <niall.litchfield@xxxxxxxxx>
  • To: tim@xxxxxxxxx
  • Date: Thu, 2 Jun 2005 21:39:38 +0100

Hi Tim
 On 6/2/05, Tim Gorman <tim@xxxxxxxxx> wrote:
> Instead of arguing about whether RAC is good at scalability or HA or
> cost-effectiveness, how about citing specifics?
> Q1 - RAC and HA:
> - What does RAC do better than any other possible solution (i.e. OS
> 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 
database requirement of RAC will give better HA. 
 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 that 
 a) you can satisfy your demand with a known number of CPUs
b) you already have that demand. 
 I see RAC as being a killer app for folk who *right now* need say 2 or 4 
cpus but may well need 8,16 or 32 as business takes off. If you go the 
single instance route then what do you do, buy four times as much hardware 
as you currently need just in case? In addition for people who don't know 
what their cpu and memory requirements actually are RAC might well make 
sense. (or they have platform limitations about how much hardware their os 
can sensibly address on a given node.) If i'm right the bundling of RAC with 
SE in 10g makes a huge amount of sense. 
 as for cost-effectiveness, as i was trying probably imperfectly to say, 
make sure you are comparing different solutions to the same business 

Niall Litchfield
Oracle DBA


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