RE: Check if async_io is enabled at disk-level

This is a pretty old thread but if you still haven't figured this one out you can use the Unix 'truss' command to see the kernel calls. If you are using async IO you should see it in the truss output. See man pages for help. I usually use something like 'truss -p {pid} -Ff.  

            -Randy  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Deepak Sharma
Sent: Tuesday, September 16, 2008 11:12 AM To: Jon.Crisler_at_usi.com; oracle-l_at_freelists.org Subject: Re: Check if async_io is enabled at disk-level  

It is set as follows:

SQL> show parameter filesystemio_options

NAME                                 TYPE        VALUE
------------------------------------ -----------
------------------------------
filesystemio_options                 string      asynch

 

• Original Message ---- From: "Crisler, Jon" <Jon.Crisler_at_usi.com> To: sharmakdeep_oracle_at_yahoo.com; oracle-l_at_freelists.org Sent: Tuesday, September 16, 2008 9:16:25 AM Subject: RE: Check if async_io is enabled at disk-level

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).  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Deepak Sharma
Sent: Tuesday, September 16, 2008 12:39 AM To: oracle-l_at_freelists.org
Subject: Check if async_io is enabled at disk-level  

Hi,

We are using ODM (Oracle Disk Manager) on one of our 10.2.0.3 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 :

Asynchronous-I/O-Processes
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() ?

Thanks,
Deepak    

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