Re: Disk Async IO

  • From: "Zhu,Chao" <zhuchao@xxxxxxxxx>
  • To: dbvision@xxxxxxxxxxxx
  • Date: Sat, 9 Sep 2006 10:27:59 +0800

It looks to me the only filesystem HP is now supporting, is VXFS.

HP-UX 11i offers customers the following choice of products:
 »  OnlineJFS (equivalent to VERITAS
 »  VERITAS Volume Manager
 »  VERITAS Cluster Volume Manager (CVM) - provides clustering capability
on top of 
 »  Logical Volume Manager (LVM) which is included in
 »  Mirrordisk/UX - provides mirroring capability for

 HP will continue its investment in LVM to meet the requirements of our
large customer base. For customers who need host-based advanced volume
management functionality and a common host-based solution across
heterogeneous operating systems, HP offers VxVM integrated with HP-UX 11i

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 -- //

Zhu Chao

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