Re: Oracle Myths

Connor McDonald wrote:

> 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
> > >
>
> adding complexity the whole scenario is that you get a 9G drive and it
> was made by vendor x, has rotation y, tranfer time z, et al, and the 18G
> drive comes from vendor p, rotation q, and you can only have 'b' 9G
> drives on the controller which runs at 'a' Hz, whereas the 18G drives
> run on the new 'c' controller with 'd' Hz.. blah blah blah
>
> .. all of which is moot, when the budget department purchase a single
> 800G drive because it was cheaper :-)
>
> Cheers
> --
> ==============================
> Connor McDonald
>
> http://www.oracledba.co.uk
>
> "Some days you're the pigeon, some days you're the statue..."

800GB? I'll bet on request they would also come on down and set it up as RAID 5 with 1MB stripes too.

Daniel Morgan Received on Tue May 21 2002 - 14:14:38 CDT