Re: blocksize on AIX

Hi,

    blocksize in aix is 4k by default, not 512 byte.     And read ahead can be controlled by aix kernel parameter. If you really want to bypass aix filesystem read ahead, just change the kernel parameter dynamically. (I cannot remember the detailed kernel parameter, maybe min/maxpgahead)).     Oracle document says db_block_size should be multiple of os_block_size, not db_block_size should be the same as os_block_size.

Zhu Chao.
www.cnoug.org.

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Friday, October 03, 2003 3:14 AM

> We use 8192 on AIX and have no problems. The AIX block size is 512 so I
> know it is advisable to have a multiple of 512, other than that I know of no
> other caveat.
>
> Ruth
> -----Original Message-----
> From: ml-errors_at_fatcity.com [mailto:ml-errors_at_fatcity.com]On Behalf Of
> Hans de Git
> Sent: Wednesday, October 01, 2003 4:24 AM
> To: Multiple recipients of list ORACLE-L
> Subject: blocksize on AIX
>
>
> Hi all,
>
> 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.
>
> 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?
>
> HTH,
> Hans
>
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Author: zhu chao
  INET: chao_ping_at_vip.163.com

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