Re: Schema Placement for Purchased Apps

"Gabriel Gonzalez" <no-spam_at_no-spam.com> wrote in message news:nAqdnXD1pf0LzgijXTWcow_at_giganews.com...
> > Block size is a function of filesystem, not whim, application type, or
> > anything else.
>
> I'll agree and disagree with you there...
>
> I agree because block size should not be set on a whim, nor should it be
an
> unfounded guess.
>
> I disagree because, for example, on a file system that has a 64k physical
> block size, you could set Oracle's block size to (again, for example):
>
> 1) 8K with block multi-read of 8,
>
> 2) 2k with block multi-read of 32,
>
> 3) 64k with block multi-read of 1.
>
> As far as raw performance cost, these are equivalent (they all cause
Oracle
> to read a single os-level disk block at a time), however, there are
distinct
> pluses and minuses to using each as far as Oracle itself goes.

Hi Gabriel,

They're kinda equivalent when performing multi-block reads but what about (the typically more common) single block read ? And perhaps more importantly, what about the writes DBWRs needs to perform back to the O/S system ?

Although I can think of specific examples where you may want to break this rule (the example I use is if you have many many tiny lookup tables that benefit from small block caching and the associated reduction in I/O rotation latency) the general recommendation is to match your block size with the I/O buffer size.

This is all explained in Oracle's Performance Tuning manual and Steve Adam's Ixora site (www.ixora.com.au).

Cheers

Richard Received on Thu Apr 10 2003 - 08:49:43 CDT