My dear friend Mogens,
I am so glad we share the same kind of "bedtime
reading" in our own parts of the world. I totally
agree with you, every cache hit ratio and performance
metric within Oracle needs to be 42, for us to be in a
sublime and happy state...;-). After all "42" does
solve all of life's problems!!
Cheers,
Gaja
- Mogens Nørgaard <mln_at_miracleas.dk> wrote:
> I always thought 42 was a good number. Perhaps I was
> wrong.
>
> Bjørn Engsig wrote:
>
> >Cary Milsap from hotsos has much data to confirm an
> approximate 1:100 ratio
> >between LIO time and PIO time.
> >
> >Can we therefore conclude, that the buffer cache
> hit ratio should be 99%? :-)
> >
> >Rgds, Bjørn.
> >On Wednesday 20 March 2002 10:48, Connor McDonald
> wrote:
> >
> >>Some rudimentary testing on a laptop here (500Mhz,
> >>512M RAM, typical single disk)
> >>
> >>a) visiting a single block via 4,000,000 logical
> IO's
> >>got me approx 35000 gets/sec
> >>
> >>b) repeated full table scans similar system got me
> >>approx 350 phys reads/sec
> >>
> >>After this extensive, thorough and exhaustive
> >>exercise, I can definitely say that memory access
> >>versus disk access (as it pertains to Oracle) is
> 100
> >>times faster on this machine in single user mode
> >>
> >>I think we can generalise this to be the rule for
> all
> >>servers under all conditions :-)
> >>
> >>Connor
> >>
> >> --- "Freeman, Robert " <Robert_Freeman_at_csx.com>
> >>wrote: > I've heard the disk vs. memory arguments
> >>before, but
> >>
> >>>never have seen
> >>>quantifiable data either way... if anyone has
> any,
> >>>I'd love to see it.
> >>>
> >>>RF
> >>>
> >>>Robert G. Freeman - Oracle8i OCP
> >>>Oracle DBA Technical Lead
> >>>CSX Midtier Database Administration
> >>>
> >>>The Cigarette Smoking Man: Anyone who can appease
> a
> >>>man's conscience can
> >>>take his freedom away from him.
> >>>
> >>>
> >>>
> >>>-----Original Message-----
> >>>Sent: Monday, March 18, 2002 5:54 PM
> >>>To: Multiple recipients of list ORACLE-L
> >>>
> >>>
> >>>Robert - So THAT is the title of your next book.
> I'm
> >>>primed to buy it
> >>>already.
> >>>I just recalled a legend, maybe. "Disk is 10,000
> >>>times slower than memory,
> >>>so memory access times are infinitesimal compared
> to
> >>>disk access". Cary
> >>>Millsap covers this in his Hotsos Clinic. He has
> run
> >>>tests that prove "ain't
> >>>so". The point is that you can't just use ratios
> to
> >>>tune Oracle, but need to
> >>>look at wait times.
> >>>Dennis Williams
> >>>DBA
> >>>Lifetouch, Inc.
> >>>dwilliams_at_lifetouch.com
> >>>
> >>>
> >>>-----Original Message-----
> >>>Sent: Monday, March 18, 2002 1:04 PM
> >>>To: Multiple recipients of list ORACLE-L
> >>>
> >>>
> >>>So, does the CoO (Church of Oracle) have an
> >>>infallibility doctrine then???
> >>>
> >>>... From the Book of Oracle, chapter 5 ...
> >>>
> >>>...and the DBA did look upon his database, and he
> >>>saw it was good.
> >>>His tablespace datafiles being distributed tither
> >>>and fro, spread amongst
> >>>the
> >>>platters of his disks. And he did complete that
> >>>which was called
> >>>documentation,
> >>>and then he rested from his labors, and drank
> >>>Mountain Dew Code Red...
> >>>
> >>>:-)
> >>>
> >>>Robert G. Freeman - Oracle8i OCP
> >>>Oracle DBA Technical Lead
> >>>CSX Midtier Database Administration
> >>>
> >>>The Cigarette Smoking Man: Anyone who can appease
> a
> >>>man's conscience can
> >>>take his freedom away from him.
<stuff deleted>
Gaja Krishna Vaidyanatha
Director, Storage Management Products,
Quest Software, Inc.
Co-author - Oracle Performance Tuning 101
http://www.osborne.com/database_erp/0072131454/0072131454.shtml
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Received on Wed Mar 20 2002 - 08:03:27 CST
