Re: AIX pinned memory

From: Mladen Gogala <mgogala_at_verizon.net>
Date: Thu, 14 Dec 2006 21:10:41 -0500
Message-id: <1166148641l.3144l.0l@medo.noip.com>

On 12/14/2006 05:46:19 PM, Allen, Brandon wrote:

>
> And I'm not sure, but the vmstat man page leads me to believe that this
> pool may include FS buffers,

This may be the key: if buffer pages are dynamically pinned an FILESYSTEMIO_OPTIONS is not set to DIRECTIO or SETALL, then the difference you're seeing might be explained by AIX file system buffers used to cache database files. I assume that your database is on JFS2, which supports not only direct and asynchronous I/O but also something called "concurrent I/O" which additionally speeds up I/O from shared memory segments. Actionable advice: set your FILESYSTEMIO_OPTIONS parameter to SETALL (there is no reason not to do so on AIX) and see whether the number of pinned pages has decreased.

-- 
Mladen Gogala
http://www.mladen-gogala.com

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Received on Thu Dec 14 2006 - 20:10:41 CST