topic Re: Anybody using DISK_ASYNC_IO in Oracle 8i? in Operating System - HP-UX

Anybody using DISK_ASYNC_IO in Oracle 8i?

Greg OBarr — Wed, 26 Mar 2003 17:55:24 GMT

I was reading up on Oracle Tuning for RMAN and this seems to add to RMAN performance significantly. I found this on ITRC
http://bizforums.itrc.hp.com/cm/QuestionAnswer/0,,0xd26242308663d611abdb0090277a778c,00.html

Is this all you need to do to turn on Asynchronous IO in HP-UX? No kernel parameters?

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Ross Zubritski — Wed, 26 Mar 2003 18:43:55 GMT

That is correct, the DISK_ASYNC_IO is an oracle parameter, not an OS parameter.

Regards,

RZ

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Greg OBarr — Wed, 26 Mar 2003 19:03:20 GMT

I am also looking in Metalink, and I see this, which indicates that you have to "configure async driver" and remake the kernel. ?? still looking...

===============================================
From Metalink Doc ID: 59668.999

Thread Status: Closed

From: Christopher Duston 15-Feb-00 22:56
Subject: disk_async_io

RDBMS Version: V8.1.5
Operating System and Version: HP-UX 11.0
Error Number (if applicable):
Product (i.e. SQL*Loader, Import, etc.): RDBMS
Product Version:

disk_async_io

8.1.5 on HP-UX 11.0 with file systems on EMC disk subsystem with memory cache on the controllers.

Do not have /dev/async. Have created multiple db writers. By default disk_async_io is true.

1) should I set disk_async_io to false?

2) Does the EMC subsystem allow me to take advantage of disk_async_io? I was under the impression
that disk_async_io is only for raw devices.

TIA,

Chris

--------------------------------------------------------------------------------

From: Oracle, Anand Viswanathan 18-Feb-00 07:21
Subject: Re : disk_async_io

Hi,

You can configure for async io in HP machine.

configure async driver and regen HP-UX
kernel
/sbin/mknod /dev/async c 101 0x0
chown oracle:dba /dev/async
chmod 660 /dev/async

Now set the parameter disk_asynch_io=true.

I have observed some problems in setting this to true in 8.0.5.I hope
this are fixed in 8.1.5.

Thanks and Regards

Anand

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Yogeeraj_1 — Wed, 26 Mar 2003 19:05:48 GMT

hi,

There has been some issues with some early version of oracle too! Seems like they have been resolved in newer versions (8i+)

basically, to configure you need to:

configure async driver and regen HP-UX kernel
/sbin/mknod /dev/async c 101 0x0
chown oracle:dba /dev/async
chmod 660 /dev/async

Now set the parameter disk_asynch_io=true in your init.ora.

Regards
Yogeeraj

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Greg OBarr — Wed, 26 Mar 2003 19:28:17 GMT

Thanks for replies. I have seen this in other posts, but what exactly is required to accomplish the following line:

configure async driver and regen HP-UX kernel

???

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Steven E. Protter — Wed, 26 Mar 2003 21:04:38 GMT

That driver should already be turned on in the kernel.

There is something else you need to do, allow for memory lock allocation in asynchronous mode.

setprivgrp dba MLOCK

dba is the group of the user that owns oracle

or

/etc/privgrp

dba MLOCK

The second solution will handle it at system startup.

Everything else should be okay, don't forget the java patches required for oracle at http://www.hp.com/go/java

And the required OS patches for oracle in doc 43057.1 on metalink.oracle.com

SEP

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Greg OBarr — Tue, 10 Feb 2004 09:53:30 GMT

FYI, when I enabled this in Oracle and HP-UX, it still didn't use async I/O. I had messages in the Oracle Alert Log (don't remember that exact message). If I remember correctly, further investigation revealed that in HP-UX, you have to use RAW partitions for your Oracle data in order to use Async I/O. I do not want to use raw partitions.

What I ended up doing is disabling the VXFS cache by mounting the Oracle data filesistems with these options:

delaylog,nodatainlog,mincache=direct,convosync=direct

and bumping up the Oracle buffer cache.

Re: Anybody using DISK_ASYNC_IO in Oracle 8i?

Volker Borowski — Tue, 10 Feb 2004 12:59:03 GMT

:-)
Bumping up the Oracle Cache is always a good idea.

In general if you want to use async io, the recommendation is to use it via OS/Kernel-Level.
Just in cases where you cant use it through kernel, you can alternative set up the Oracle Parameters for this.
It is not recommended (I mind to remember even not supported, but not sure about this) to run both, Oracle async configuration AND Kernel async-io.

Hope this helps
Volker