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mhoys
 
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Default Async IO bug - 09-02-2010 , 03:19 AM






Hi,

After the installation of patch set 10.2.0.5, we seem to be hitting
bug 9949948: "Linux: Process spin under ksfdrwat0 if OS Async IO not
configured high enough". And even after several hits it won't die.
According to MOS, the workarounds are:
1) increase aio-max-nr on the OS level
2) disable async_io on the database level

We are on Red Hat 4 and apparently it's not possible to increase aio-
max-nr on this operating system? It's now set to 65536. I'm not really
in favor of disabling async_io for performance reasons...

Anyone else having the same problem and how did you solve this?

Thanks,
Matthias Hoys

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Mladen Gogala
 
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Default Re: Async IO bug - 09-02-2010 , 07:40 AM






On Thu, 02 Sep 2010 01:19:14 -0700, mhoys wrote:

Quote:
We are on Red Hat 4 and apparently it's not possible to increase aio-
max-nr on this operating system? It's now set to 65536.
Why wouldn't it be possible to increase aio-max-nr?

$>cd /proc/sys/fs
ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
$>cat aio-max-nr
300000
ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
$>cat /etc/redhat-release
Red Hat Enterprise Linux AS release 4 (Nahant Update 2)
ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs


--
http://mgogala.byethost5.com

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Mark D Powell
 
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Default Re: Async IO bug - 09-02-2010 , 09:26 AM



On Sep 2, 8:40*am, Mladen Gogala <gogala.mla... (AT) gmail (DOT) com> wrote:
Quote:
On Thu, 02 Sep 2010 01:19:14 -0700, mhoys wrote:
We are on Red Hat 4 and apparently it's not possible to increase aio-
max-nr on this operating system? It's now set to 65536.

Why wouldn't it be possible to increase aio-max-nr?

$>cd /proc/sys/fs
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
*$>cat aio-max-nr
300000
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
*$>cat /etc/redhat-release
Red Hat Enterprise Linux AS release 4 (Nahant Update 2)
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs

--http://mgogala.byethost5.com
Lots of places run RedHat and have async IO in use. I would double
check all the kernal parameters against the Installation Guide
requirements.

HTH -- Mark D Powell --

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  #4  
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mhoys
 
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Default Re: Async IO bug - 09-02-2010 , 09:35 AM



On Sep 2, 2:40*pm, Mladen Gogala <gogala.mla... (AT) gmail (DOT) com> wrote:
Quote:
On Thu, 02 Sep 2010 01:19:14 -0700, mhoys wrote:
We are on Red Hat 4 and apparently it's not possible to increase aio-
max-nr on this operating system? It's now set to 65536.

Why wouldn't it be possible to increase aio-max-nr?

$>cd /proc/sys/fs
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
*$>cat aio-max-nr
300000
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs
*$>cat /etc/redhat-release
Red Hat Enterprise Linux AS release 4 (Nahant Update 2)
*ADPRD1@oracle14 oracle Last rc=0 /proc/sys/fs

--http://mgogala.byethost5.com
You are right! It can be changed on Red Hat 4.
Guess I have been confusing AIO-MAX-NR with AIO-MAX-SIZE! Stupid me...

Matthias

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