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Re: mixing jfs and jfs2 filesystems

From: Mladen Gogala <mgogala_at_yahoo.com>
Date: Sat, 3 Nov 2007 21:51:15 +0100 (CET)
Message-ID: <fgin03$1vv$1@aioe.org>


On Wed, 31 Oct 2007 07:59:50 -0700, Ben wrote:

> I've read that setting filesystemio_options=setall will let oracle
> determine how it accesses datafiles but in doing that it will cause any
> files on jfs filesystems to be accessed via dio. Has anyone here had any
> experience with running a database using jfs & jfs2 without cio or dio
> set and having aio turned on for the server? What did you have
> filesystemio_options set to? Does it work?

I've been using JFS on Linux for years and turning both direct and async I/O on works flawlessly. Using direct I/O on a set of files doesn't impact how the other files are open, at least on Linux. AIX is, according to my experience, extremely stable and well written operating system, I doubt that it would behave differently in that respect from a Linux vulgaris.

You can find an excellent paper about the JFS file system here: http://www-03.ibm.com/systems/p/os/aix/whitepapers/db_perf_aix.pdf

JFS(and JFS2, of course) can support direct I/O without any additional mount options. Asynchronous I/O is supported by both variants of JFS, as well. You can set your filesystemio_options to direct, async, both or none, it will work. How well it work for you - that depends on the I/O pattern produced by your application system. My experience tells me that OLTP systems benefit more from the direct I/O then the DW variety. There is, of course, a whole universe of mixed-mode applications between OLTP and DW.

-- 
Mladen Gogala
Received on Sat Nov 03 2007 - 15:51:15 CDT

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