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RE: Re[2]: os block size versus oracle bock size

From: <GKor_at_rdw.nl>
Date: Mon, 29 Oct 2001 02:37:15 -0800
Message-ID: <F001.003B6C5F.20011029013518@fatcity.com>

ok, thanks for your explanation.

> -----Oorspronkelijk bericht-----
> Van: dgoulet_at_vicr.com [SMTP:dgoulet_at_vicr.com]
> Verzonden: dinsdag 23 oktober 2001 17:50
> Aan: Multiple recipients of list ORACLE-L
> Onderwerp: Re[2]: os block size versus oracle bock size
>
> WHOA, No that is not a performance problem. The Oracle block size needs
> to
> always be a multiple of the OS block size. Most operating systems today,
> W2K
> being no exception, do not simply read the number of OS blocks that you
> request.
> They always 'read ahead' in the anticipation that you'll want that data
> in the
> very near future. The amount of read ahead that is done is OS specific.
> Therefore if your Oracle block size is <= the OS block size the operating
> system
> will be doing a lot of reading for you that is irrelevant, which can lead
> to a
> phantom performance problem namely your wasting OS reads. The idea here
> is to
> pick an Oracle block size that is appropriate for your application and a
> multiple of the OS block size. Also set db_file_multiblock_read_count
> carefully
> since this controls the number of blocks that Oracle requests from the OS
> at one
> time. If you need one block and have db_file_multiblock_read_count set to
> 100,
> then you get 100 blocks, if the OS allows.
>
> Dick Goulet
>
> ____________________Reply Separator____________________
> Author: nlzanen1_at_EY.NL
> Date: 10/23/2001 7:05 AM
>
>
> Hi
>
>
> I'd say yes. For every Oracle block read the OS has to read two block
> which
> causes overhead.
>
>
> Jack
>
>
>
>
> GKor_at_rdw.nl_at_fatcity.com on 23-10-2001 16:05:21
>
> Please respond to ORACLE-L_at_fatcity.com
>
> Sent by: root_at_fatcity.com
>
>
> To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> cc: (bcc: Jack van Zanen/nlzanen1/External/MEY/NL)
>
> hi all
>
> we have an oracle block size of 8k and i believe our W2K server has a
> default
> os block size of 4k.
> Is this a problem with the performance ?
>
> thanks
>
>
> g.g. kor
> rdw ict groningen
>
>
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> INET: GKor_at_rdw.nl
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> Author:
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  INET: GKor_at_rdw.nl

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Received on Mon Oct 29 2001 - 04:37:15 CST

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