Re: Buffer cache statistics (ratios) and CBO SQL optimization?

Noons wrote:
>
> "Connor McDonald" <connor_mcdonald_at_yahoo.com> wrote in message news:3FF275DD.3F0_at_yahoo.com...
>
> > Some figures from machines I've played with in the past
> >
> > Machine LIO/sec PIO/sec
> > Home PC, 500Mhz 34,950 340
> > HP, 266 Mhz 26,770 650
> > HP, 650 Mhz 74,850 2780
> > HP, 750 Mhz, 83,150 2840
> > Compaq, 700Mhz 66,470 3380
>
> The Compaq numbers are quite surprising. The LIO is lower
> than others of similar speed, but the PIO is much faster.
> I wonder: was that an Alpha?
>
> With the exception of the home PC, the numbers seem to
> confirm JL's claim of 10K LIO/s for each 100MHz. They
> are certainly around those figures.
>
> Do you recall what size was the PIO? I can pump small blocks
> from my new 80Gb drive higher than that 340, nowadays. Given
> ideal conditions, of course.
>
> --
> Cheers
> Nuno Souto
> wizofoz2k_at_yahoo.com.au.nospam

Can't remember the specific machines - I was preparing some numbers for a presentation so they were just the servers I had access to at the time. Ditto the PIO's - with the exception of the home PC - they were all some sort of disk array, san, etc. Similarly, most of these machines would have had other users on them at the same time, the numbers were simply the best I got over 5 or so runs.

Size of the PIO's varied between 4 and 32 multiblock reads of 8k (full scan on a table in a raw datafile). The number that came out best was the one that was used.

In terms of 340 on the home PC, suffice to say, my home PC is getting a little old, last time I had to cover off I think the disk was a 5400rpm IDE number with no special IO channels :-(

Cheers
Connor Received on Wed Dec 31 2003 - 05:59:32 CST