RE: Check if async_io is enabled at disk-level

From: Crisler, Jon <>
Date: Tue, 16 Sep 2008 10:16:25 -0400
Message-ID: <56211FD5795F8346A0719FEBC0DB067503187ADD@mds3aex08.USIEXCHANGE.COM>

Check to see what the setting is for filesystemio_options. If = setall this should turn on both async i/o and direct i/o. If this is set to "none" but disk_async_io = true then I don't know what the end result would be: perhaps filesystemio_options override disk_async_io. Also make sure you are at a recent Maintenance Pack for AIX as there are some known issues with Oracle (but I don't know specifically with AIO).  

[] On Behalf Of Deepak Sharma Sent: Tuesday, September 16, 2008 12:39 AM To:
Subject: Check if async_io is enabled at disk-level  


We are using ODM (Oracle Disk Manager) on one of our DBs, and the disk_asynch_io is TRUE in the database. I have also read that ODM supports kernel asynchronous I/O. The platform is AIX 5.3

Using 'nmon' and choosing "A = Async I/O Servers", this is what we see :

Total AIO processes= 100 Actually in use= 0

This might indicate that AIO is not happening at kernel-level.

How else can we verify if async I/O is actually happening at Kernel-level? We could possibly truss the DB Writer process(es) and check for the kernel-level calls for writes - what should we look for? Is it kiowrite() instead of plain, write() ?


Received on Tue Sep 16 2008 - 09:16:25 CDT

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