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Re: Projecting resource requirements

From: Tim Gorman <>
Date: Tue, 08 Mar 2005 02:19:15 -0700
Message-ID: <>

It doesn't deal with capacity-planning for RAM, but does work with CPU and I/O throughput predictions.

For RAM on Oracle servers, figure on at least 2Gb of RAM per CPU for older CPUs, 3x to 4x per CPU for the newer faster CPUs (over 2Ghz or so)...

on 3/7/05 4:49 PM, stephen booth at wrote:

> On Mon, 7 Mar 2005 14:00:19 -0800 (PST), David Turner <>
> wrote:

>> Can anyone point me to some documents on calculating
>> resource requirements for a project? I'm ok with disk
>> consumption but cpu and memory seem harder to project.

> I've worked with contractors who have horrendously complex
> spreadsheets they use to estimate resource requirments based on query
> types, date volumes and number of queries. They're usually wrong.
> The following advice is based on several years working on IT projects
> in the public sector. Any pessimism or cynicism you detect is the
> result of several years working on IT projects in the public sector.
> The best way to estimate is usually to find a system that is broadly
> similar, see what it's running on and how it's doing, add on a healthy
> contingency then scale up from there.
> If it's a totally new system then the way I've found is best is to
> make an educated guess based on what I can find out, add 50%. Spec a
> system based on that estimate then see what the next model up is.
> Spec for the next model up fully loaded. Identify a system that has
> the power of the last system specced and the capacity to be expanded
> to twice that power. Get a quote on that.
> So supposing you're inital guess plus 50% comes out to a Sunfire V240.
> Next model up is a V440. A half loaded V880 is about the same as a
> fully loaded V440 so that's what you get the quote for.
> If you're buying an app which the vendor has given you a spec for the
> hardware to run it on then at least triple that spec. Apps vendors
> will often under spec the kit they tell the project managers they'll
> need to buy to run the apps so as to make their product seem cheaper.
> Stephen
Received on Tue Mar 08 2005 - 04:21:11 CST

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