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Re: Oracle Myths

From: Daniel Morgan <dmorgan_at_exesolutions.com>
Date: Tue, 21 May 2002 15:06:25 GMT
Message-ID: <3CEA6265.3285A6D8@exesolutions.com>


Jonathan Lewis wrote:

> I don't think this is one where you can produce
> a definitive 'hard' proof; you can only posit a
> logical argument. Viz (and I'm sure you already
> say this to your students, Daniel):
>
> 1) I can always invent a system that requires
> a given number of real physical I/O requests per
> second, irrespective of the size of any available
> cache.
>
> 2) Real hardware devices can only support
> around 100 random I/O requests per second.
>
> 3) If I want to 10,000 I/Os per second then
> I need a minimum of 100 devices.
>
> Given the free choice between 50 x 20GB drives
> and 100 x 9 GB drives, I'd need to have the larger
> number of smaller drives. On the other hand,
> given the choice between 100 x 20 GB drives
> and 100 x 9 GB drives, I'd take the larger and
> be very careful about how the spare 11GB per
> drive was used.
>
> QED
>
> In real life, of course, the calculations are rarely
> made (until it's too late), and the scale of operation
> is rarely so extreme that throwing loads of cash
> at a cache fails to make the difference.
>
> --
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
> Author of:
> Practical Oracle 8i: Building Efficient Databases
>
> Next Seminar - Australia - July/August
> http://www.jlcomp.demon.co.uk/seminar.html
>
> Host to The Co-Operative Oracle Users' FAQ
> http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>
> Daniel Morgan wrote in message <3CE987D0.A4D9D0E0_at_exesolutions.com>...
> >
> >On the face of it I can't disagree. But then I couldn't disagree initially
> >with a number of things pointed out as myths.
> >
> >Has anyone actually put this to the test and gathered the numbers ... or
> >is this unsubstantiated theory?
> >
> >The quest continues.
> >
> >Daniel Morgan
> >

Thanks,

Daniel Morgan Received on Tue May 21 2002 - 10:06:25 CDT

Original text of this message

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