Re: Check if async_io is enabled at disk-level
From: Deepak Sharma <sharmakdeep_oracle_at_yahoo.com>
Date: Tue, 16 Sep 2008 09:11:47 -0700 (PDT)
Message-ID: <522571.90872.qm@web52804.mail.re2.yahoo.com>
Date: Tue, 16 Sep 2008 09:11:47 -0700 (PDT)
Message-ID: <522571.90872.qm@web52804.mail.re2.yahoo.com>
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 dont 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 dont 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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