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

2001-10-29 Thread GKor

ok, thanks for your explanation.

> -Oorspronkelijk bericht-
> Van:  [EMAIL PROTECTED] [SMTP:[EMAIL PROTECTED]]
> 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: [EMAIL PROTECTED]
> 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
> 
> 
> 
> 
> [EMAIL PROTECTED]@fatcity.com on 23-10-2001 16:05:21
> 
> Please respond to [EMAIL PROTECTED]
> 
> Sent by:  [EMAIL PROTECTED]
> 
> 
> To:   Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> 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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Re[2]: os block size versus oracle bock size

2001-10-23 Thread dgoulet

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: [EMAIL PROTECTED]
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




[EMAIL PROTECTED]@fatcity.com on 23-10-2001 16:05:21

Please respond to [EMAIL PROTECTED]

Sent by:  [EMAIL PROTECTED]


To:   Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
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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derden is, behoudens voorafgaande schriftelijke toestemming van Ernst &
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