Re: Disk Async IO

  • From: BN <bnsarma@xxxxxxxxx>
  • To: dbvision@xxxxxxxxxxxx
  • Date: Fri, 8 Sep 2006 09:28:55 -0400

On 9/7/06, Nuno Souto <dbvision@xxxxxxxxxxxx> wrote:

BN wrote,on my timestamp of 7/09/2006 4:54 AM:

> I remember reading Oracle Metalink  Notes saying that Disk Async IO is
> not supported on HP-UX for Cooked Filesystems.

you're correct in the Metalink references. But there is no such
thing as "cooked filesystems".
There is "raw" IO and "cooked" IO: the first is *without*
filesystems, the second *with* filesystems.

> We have disk_async_io=true for our Database in HP-UX 11.11 , Oracle > <> and 10g Servers.

won't do a thing for you unless you're using raw database files - with
no file system associated, just the device name used as datafile
name in Oracle.

> Right now we are using 4 dbwr's. I appreciate  your suggestions.

Keep using the 4 dbwrs and lose the disk_async_io parameter:
it's doing nothing unless you're using raw IO.

> Our UNIX SA says " Cooked Filesystems have their own Asynchronous > Mechanisim that equally replaces Oracle Async IO"

I'll add my voice to Kevin's reply...

> What Am I missing here

A lot.  To get aio in filesystems in HPUX you must use
a filesystem type that supports it.  As of last time I checked
it, the only one that did in HP environments was vxfs, the
Veritas file system for HP.  None of the native HPUX ones did.
Oh: did I mention that vxfs is an extra?
As in: "mucho dinero"?

-- Cheers Nuno Souto in sunny Sydney, Australia dbvision@xxxxxxxxxxxx -- //

Greetings Nuno,

Thank you for the info.

You mean if The Filesystems are created/mounted using vxfs, then we can use
Async IO on HP-UX?

-- Regards & Thanks BN

Other related posts: