Re: Max datafile size in AIX5.2L
- From: Byron Pearce <pearceb@xxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 29 Jun 2004 10:13:05 -0500
Nuno:
I think you're referring to the post I put out on the list Friday. It
was from an IBM document on Oracle Performance Tuning that said:
"... Do not allocate a JFS with the large file enabled (bf) attribute.
The big file attribute increases the minimum DIO transfer size
(diocapbuf.dio_min returned by the finfo system call) from 4K to 128K,
forcing Oracle to read and write a minimum of 128K byte to exploit DIO.
Please note that 2GB is the largest file size applications (including
Oracle) can use in a JFS without the 'bf' attribute -- large file
enablement. Do not allocate a compressed JFS, which defeats DIO.
Respecting the JFS 2GB maximum file size avoids potential file level
inode locking performance issues in JFS or JFS2 (without CIO), but a
downside of small (2GB) files in a very large database (VLDB)
environment is the time required to open/close files during the
startup/shutdown..."
I have never encountered this type of alleged issue on any other O/S
(mainly Solaris and HPUX) so I was wondering if anyone had any
experience or comments on it. I have not been able to wrangle resources
to try and run some empirical tests at this point, but there is quite a
bit of internal discussions (not heated just yet) starting to take place
as a result of the doc.
Nuno Souto wrote:
> Wasn't there a warning a coupla days ago or so about
>
>AIX using 128Kb I/O block size (when using DIO?)
>for files >2Gb?
>
>
--
====================================================================
Byron Pearce mailto:pearceb@xxxxxxxxxx
Tenure Systems, Inc. Dallas/Fort Worth, TX
"It's hard to be a ninja when you wear a beeper."
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