Oracle-L: RE: DISK_ASYNC

From: Diego Cutrone <diegocutrone_at_yahoo.com.ar>
Date: Thu, 24 Apr 2003 15:31:38 -0800
Message-ID: <F001.00589059.20030424153138@fatcity.com>

Darrell,

I'd recomend to set it to FALSE if your entire database is on FS. Why?, because if not your OS will use threaded Async I/O, it will use some light-weight processes to SIMULATE async I/O. And that (according to my experience) has resulted in a high CPU usage and in a slow I/O response.

Of course, I'd also recomend to put (at least) your redo and temp files on raw devices and set the parameter _filesystemio_options to directio and disk_async_io=true. This will use KAIO on the raws and DirectIO on the FS. Best of both worlds

HTH
greetings
Diego Cutrone

Does anyone have any experiences to share regarding this parameter?

Here's the scenario:
We're on HP-UX with veritas file systems which means no asynchronous
I/O.
However the disk_async_io parameter is true by default. I'm wondering
if there's any reason to set this to false. I know we're not using
async io, but does this parameter pose any kind of problem or risk to
Oracle by being set to true in a non-async environment?
I've searched metalink (and am still reading through the fluff), but
haven't found this addressed.

Thanks!
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Author: Darrell Landrum
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RE: DISK_ASYNC_IO