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Re: Capacity Planning

From: LiShan Cheng <>
Date: Thu, 23 Feb 2006 12:26:29 +0100
Message-ID: <>


Thanks for the reply.

I am quite lost in this area basically becase I am quite reluctant about capacity planning since I have seen quite a few and I have seen cero success. Many times I would really like to ask the guy who did the plan how he did it without knowing so many factors.

In my last project for example, a HP guy estimated 12 CPUs for a server however in the practice we almost doubled otherwise the server would be CPU bounded.

I understand it is necessary but... whose job should it be? DBA? Hardware Vendor? Software Maker? System Admin? Mix of all is probably the answer but then what information is needed by a DBA to perform such job?

Shall I tkprof 10 sessions get the cpu time and multiply by the real number of users I will have? :-)



On 2/23/06, Jurijs Velikanovs <> wrote:

> I'm interested in that question as well. I believe almost all DBA-s
> had, have, will have to answer it.
> The most difficult for me was CPU power, I/O throughput and Memory
> planning for home made (custom development) applications
> .
> By my experience you can spend tremendous amount of time (not just
> yours time) creating capacity plan for a particular system during an
> application development time. Work with analysts, designers,
> developers documenting detailed calculations and all assumptions. But
> end of the day you will get, a +/- 50% accurate result ;).
> If at the end the applications will not perform well enough the
> Developers will blame HW and will some think like "You need double HW
> resources to get XX sec response time". DBA-s and Admins would say "We
> already have some thing like top HW". It is always difficult to say if
> developers have done their work well without knowing the applications
> business.
> .
> At the moment I think that most effective way to plan that type of
> capacity is make assumptions based on you or others project members'
> previous experience.
> - If in the past you have worked with kind of systems you currently
> developing you know already the most important parts of application
> you have to pay attentions. This is there you have to concentrate your
> attention. In most cases it is something like 2% of overall
> application code. Describe, prototype, play with that bit and of the
> day you will get -/+ 10% accurate planning.
> - If in the past you have worked with much bigger systems, with huge
> amount of data processing you can think like. This system is 5 times
> smaller the system I have worked with. Presumably this system will run
> successfully on 2-3 times smaller HW and we will spend 2 times less
> time to tune it.
> - If you have chance to get information about system like you are
> going to implement (like OEBS, SAP, or other pre developed
> application, or the same functional application, or old system you
> going to replace), you can base your assumption on that information.
> .
> Later on then Developers will say you haven't enough HW capacity, you
> would be able to base you conclusion on a comparison of the developed
> application and other systems.
> .
> I don't think this approach is ideal, but at the moment I haven't found
> better.
> I would be glad to hear others opinion.
> Thank you in advance,
> Jurijs
> On 2/23/06, LiShan Cheng <> wrote:
> > Hi
> >
> > I was wondering if anyone know any source about effective Oracle RDBMS
> > Capacity Planning. I mean effective because in the past I have seen many
> so
> > called "Capacity Plan" which failed miserably in the practice. I am not
> sure
> > how can a DBA perform Capacity Planning without knowing much about the
> > application?
> >
> > Cheers
> >
> >
> > LSC
> >
> >
> --
> Jurijs
> +44 7738 013090 (GMT)
> ============================================
Received on Thu Feb 23 2006 - 05:26:29 CST

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