RE: Linux RAC and asynch io - OCFS & "filesystemio_options" parameter?
- From: "Marquez, Chris" <CMarquez@xxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Fri, 14 Jan 2005 15:06:01 -0500
Confiliting info/dates:
-------------
Note:252331.1
Last Revision Date: 16-APR-2004
"as of ocfs 1.0.9-4 ocfs as a filesystem supports async io
functionality."
-------------
Note:240575.1
Last Revision Date: 03-MAY-2004
"Presently Async I/O is not available for the Oracle Clustered File
System(OCFS),
...
Make sure that all Oracle datafiles reside on filesystems that support
asynchronous I/O.
(For example, ext2, ext3)
disk_asynch_io=3Dtrue (default value is true)
filesystemio_options=3Dasynch"
My config;
9205
ocfs 1.0.13-1
Anyone want to take a guess as to what "filesystemio_options" should be
set to?
Could find a direct answer on Metalink...I would guess
"filesystemio_options=3Dasynch",
because my (Cluster) filesystem supports async IO?
PS I found no posted issues regarding database crashes, Linux & async
I/O!?
Chris Marquez
Oracle DBA
HEYMONitor(tm) - heymonitor.com
"Oracle Monitoring & Alerting Solution"
FUL NOTE DEATAILS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
METALINK
----------
Doc ID: Note:252331.1
Subject: Update on OCFS for Linux
Last Revision Date: 16-APR-2004
Support for Async IO.
as of ocfs 1.0.9-4 ocfs as a filesystem supports async io functionality.
However, the oracle rdbms code disables asyncio, even when linked in.
There is a patch in the works that can be applied on top of 9.2.0.4 to
re-enable async io on ocfs.
This first needs to go through a round of testing.
----------
Doc ID: Note:240575.1
Subject: RAC on Linux Best Practices
Last Revision Date: 03-MAY-2004
? Using Asynchronous I/O
Asynchronous I/O can be used on RAWIO, EXT2, EXT3, REISERFS filesystem.
Asynchronous IO is not supported on NFS.
Presently Async I/O is not available for the Oracle Clustered File
System(OCFS),
because the Linux kernel does not expose the API needed.=20
We hope the API is exposed in the RedHat 3.0 release, so OCFS can
support asynchronous I/O.
To enable asynchronous I/O for Oracle9iR2 on Red Hat Linux Advanced
Server 2.1 and
United Linux 1.0 you must re-link Oracle using the Async I/O library,
libaio, as follows:
cd to $ORACLE_HOME/rdbms/lib
make -f ins_rdbms.mk async_on
make -f ins_rdbms.mk ioracle
Two parameters in the init.ora need to be changed, add following lines
to the appropriate init.ora file:
---Parameter settings in init.ora for raw devices:
disk_asynch_io=3Dtrue (default value is true)
---Parameter settings in init.ora file or spfile.ora for filesystem
files:
Make sure that all Oracle datafiles reside on filesystems that support
asynchronous I/O. (For example, ext2, ext3)
disk_asynch_io=3Dtrue (default value is true)
filesystemio_options=3Dasynch
To get better I/O throughput:
For DSS workloads, the /proc/sys/fs/aio-max-size has to be increased
from the default 131072 bytes to >=3D1M.
For OLTP workloads, the default size of 131072 would suffice, as these
workloads perform very small writes.
You can set this value by executing the following command as root user:
echo >/proc/sys/fs/aio-max-size 1048576
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Marquez, Chris
Sent: Friday, January 14, 2005 1:50 PM
To: thump@xxxxxxxxxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: RE: Linux RAC and asynch io/IO slaves
David,
Thanks for the info...I going to check metalink too, but go relink
sometime today and run some laod tests.
Chris Marquez
Oracle DBA
HEYMONitor(tm) - heymonitor.com
"Oracle Monitoring & Alerting Solution"
-----Original Message-----
From: delysid@xxxxxxxxxxxxxxxxxxxx [mailto:delysid@xxxxxxxxxxxxxxxxxxxx]
On Behalf Of David
Sent: Friday, January 14, 2005 1:05 PM
To: thump@xxxxxxxxxxxxxxxx
Cc: Marquez, Chris; matthewp@xxxxxxxxxx; oracle-l@xxxxxxxxxxxxx
Subject: RE: Linux RAC and asynch io/IO slaves
Everything I have read advocates aio on RHAS 3.0.
I have heard also it can cause crashes and corruption, but found no meat
to that statement no open bugs for 9205/9206 on rhas 3.0 Anyone with any
hard facts as to real issues or successes? Anyone done an IO slave
implementation in Linux/RAC? IO slaves in many ways are more robust and
multi purpose than asych IO functionality...but I'm wondering how that
performs with RAC.
Yes, I would and will test either or both before consideration with
prod, but looking for others insights if they have been down the road.
--
..
David
>>
>> Matthew,
>>
>>>>bugs related to 9i RAC on Linux and asynch io
>>
>> Can you point to any (bugs) specifically or should I just search=3D20 =
>> Metalink?
>>
>> I was considering enabling this for my 9iRAC/RHEL3ES...Oracle=3D20=20
>> (marketing, presentations) imply that I should be doing this. Frankly
>> Oracle Corp. takes much credit for helping RH/Linux get to async-IO?
>>
>> Thanks,
>>
>> Chris Marquez
>> Oracle DBA
>> HEYMONitor(tm) - heymonitor.com
>> "Oracle Monitoring & Alerting Solution"
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