Oracle-L: Re: BAARF

From: Thomas Day <tday6_at_csc.com>
Date: Mon, 29 Sep 2003 06:04:46 -0800
Message-ID: <F001.005D15DC.20030929060446@fatcity.com>

My struggle is not with the directory layout OFA.

It is with the "mythical" OFA that every DBA that I have talked to knows all about. Where ORACLE says that if you are a good and competent DBA you will separate your table data and your index data into two separate tablespaces so that one disk head can be reading index entries while another disk head is reading the table data. You've never run into that?

                                                                                                                                       
                      Tim Gorman <tim                                                                                                  
                      @sagelogix.com>          To:      Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>                    
                      Sent by:                 cc:                                                                                     
                      ml-errors                Subject: Re: BAARF                                                                      
                                                                                                                                       
                                                                                                                                       
                      09/28/2003 09:44                                                                                                 
                      PM                                                                                                               
                      Please respond                                                                                                   
                      to ORACLE-L

Thomas,

Please pardon me, but you are off-target in your criticisms of OFA.

It has never advocated separating tables from indexes for performance purposes. Ironically, your email starts to touch on the real reason for separating them (i.e. different types of I/O, different recovery requirements, etc). Tables and indexes do belong in different tablespaces, but not for reasons of performance.

Cary first designed and implemented OFA in the early 90s and formalized it into a paper in 1995. Quite frankly, it is a brilliant set of rules of how Oracle-based systems should be structured, and a breath of fresh air from the simplistic way that Oracle installers laid things out at the time. It took several years for Oracle Development to see the light and become OFA-compliant, and not a moment too soon either. Just imagine if everything
were still installed into a single directory tree under ORACLE_HOME? All of things you mention here have nothing to do with OFA.

Please read the paper.

Hope this helps...

-Tim

P.S. By the way, multiple block sizes are not intended for performance

        optimization;  they merely enable transportable tablespaces between
        databases with different block sizes.

on 9/25/03 11:04 AM, Thomas Day at tday6_at_csc.com wrote:

>
> I would love to have a definitive site that I could send all RAID-F
> advocates to where it would be laid out clearly, unambiguously, and
> definitively what storage types should be used for what purpose.
>
> Redo logs on RAID 0 with Oracle duplexing (y/n)?
> Rollback (or undo) ditto?
> Write intensive tablespaces on RAID 1+0 (or should that be 0+1)?
> Read intensive tablespaces on RAID ? (I guess 5 is OK since it's cheaper
> than 1+0 and you won't have the write penalty)
>
> While we're at it could we blow up the OFA myth? Since you're
tablespaces
> are on datafiles that are on logical volumns that are on physical devices
> which may contain one or many actual disks, does it really make sense to
> worry (from a performance standpoint) about separating tables and indexes
> into different tablespaces?
>
> We have killed the "everything in one extent" myth haven't we?
Everybody's
> comfortable with tables that have 100's of extents?
>
> And while we're at it, could we include the Oracle 9 multiple blocksizes
> and how to use them. The best that I've seen is indexes in big blocks,
> tables in small blocks --- uh, oh, time to separate tables and indexes.
>
> Maybe we will never get rid of the OFA myth.
>
> Just venting.
>
> Tired of arguing in front of management with Oracle certified DBAs that
> RAID 5 is not good, OFA is unnecessary, and uniform extents is the only
way
> to go. Looking for a big stick to catch their attention with.
>

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Author: Tim Gorman
  INET: tim_at_sagelogix.com

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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Thomas Day
  INET: tday6_at_csc.com

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Received on Mon Sep 29 2003 - 09:04:46 CDT