Re: CBO influences

Connor McDonald wrote:

>>Don't share a SAN if you want to run a high
>>performance OLTP system - they're not very
>>good for small, highly randomised I/Os.
>>
>>--
>>Regards
>>
>>Jonathan Lewis
>>
>>http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html
>>Cost Based Oracle - Volume 1: Fundamentals
>>On-shelf date: Nov 2005
>>
>>http://www.jlcomp.demon.co.uk/faq/ind_faq.html
>>The Co-operative Oracle Users' FAQ
>>
>>http://www.jlcomp.demon.co.uk/appearances.html
>>Public Appearances - schedule updated 4th Sept 2005

> 
> 
> I would generalise to SAN's are not good at IO... period
> 
> :-)

That has not been my experience.

What I have found is that often storage admins say to the DBA: "You asked for 60 gigs ... I gave you 60 gigs" and put it all on one 400GB disk or one LUN.

Properly configured the story changes dramatically.

Kent Stroker, formerly Oracle's SE of the year (two years in a row) and an expert on RAC and storage has many times during his public lectures stated that the one of the biggest tuning problem facing most installations he sees is improperly presented disks. There is no operating system or Oracle instrumentation capable of telling you that the storage admin made bad decisions. So often we end up tuning, as best we can, given what we got.

-- 
Daniel A. Morgan
http://www.psoug.org
damorgan_at_x.washington.edu
(replace x with u to respond)