RE: Check if async_io is enabled at disk-level
- From: "Randy Johnson" <oraclelist@xxxxxxxxxxxxx>
- To: <sharmakdeep_oracle@xxxxxxxxx>, <Jon.Crisler@xxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 27 Oct 2008 07:29:56 -0600
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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Deepak Sharma
Sent: Tuesday, September 16, 2008 11:12 AM
To: Jon.Crisler@xxxxxxx; oracle-l@xxxxxxxxxxxxx
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@xxxxxxx>
To: sharmakdeep_oracle@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Deepak Sharma
Sent: Tuesday, September 16, 2008 12:39 AM
To: oracle-l@xxxxxxxxxxxxx
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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