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Re: blocksize on AIX

From: Tanel Poder <tanel.poder.003_at_mail.ee>
Date: Wed, 01 Oct 2003 09:34:48 -0800
Message-ID: <F001.005D1B37.20031001093448@fatcity.com>


> I've read on ixora.com.au and other sites that the optimal block size for
> AIX is 4K, because JFS pages are 4K also.

Isn't JFS block size changeable?

>
> Has anyone of you ever experienced performance problems on AIX due to a
> larger blocksize? What exactly are the 'read ahead' issues and cpu
problems
> regarding double buffering etc. Are there any alternatives, other than
> moving to raw volumes?

I think read ahead problems on 4k file system with 8k block size might mean that some operating systems will do readahead caching when they see more than one consecutive block requested from file system. So, every oracle single-block read will actually result in much larger read by OS. This isn't that bad when Oracle itself is doing big multiblock reads, but for single block reads it might cause performance problems.

Tanel.

>
> HTH,
> Hans
>
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-- 
Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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Received on Wed Oct 01 2003 - 12:34:48 CDT

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