Re: Performance difference between 2 machines

From: Fabrizio <fabrizio.magni_at_mycontinent.com>
Date: Thu, 23 Jun 2005 15:32:39 +0200
Message-ID: <42baba75$0$75191$892e7fe2@authen.white.readfreenews.net>

sybrandb_at_yahoo.com wrote:
> Contrary to you I don't think *SIMULATING* aio the same as aio.
> Also, contrary to you, I did test. It was faster without disk_async_io
> = true on vxfs.

Weird: sunsolver note #17818
(http://sunsolve.sun.com/search/document.do?assetkey=1-9-17818-1) states kaio is supported even on vxfs...

However you should have been tested with filesystemio_options=none and filesystemio_options=async.
That's the variable to use when dealing with async i/o on cooked devices.

> As far as I am concerned, you are simply incorrect: the article is
> clearly stating the Oracle kernel *simulates* aio (after the initial
> kaio call failed). I have demonstrated it actually was slower. Not sure
> why you insist on contradicting me.
> I usually don't make up fairy tales.
>

Sybrand, nothing personal but so far you haven't demostrated anything.

So: I borrowed a developer machine (SunOS bretesdbss01 5.8 Generic_117350-06 sun4u sparc SUNW,Ultra-4 with oracle Release 9.2.0.6.0).

Below you can see the result.
I preferred to execute the no-async test after the async one so I gave you the advantage of filesystem caching (I didn't whish to read any "you cheated because...").

Then I repeated the first test (several times) to understand if I obtained it "by luck.

ORARAS> create table remedy.foo as select * from cdg.societa;

Table created.

Elapsed: 00:00:00.86
ORARAS> drop table remedy.foo;

Table dropped.

Elapsed: 00:00:00.49
ORARAS> show parameter filesystem

NAME                                 TYPE        VALUE
------------------------------------ ----------- 
------------------------------
filesystemio_options                 string      asynch

ORARAS> alter system set filesystemio_options=none scope=spfile;

System altered.

Elapsed: 00:00:00.22
ORARAS> startup force
ORACLE instance started.

Total System Global Area 655854584 bytes

Fixed Size                   732152 bytes
Variable Size             318767104 bytes
Database Buffers          335544320 bytes
Redo Buffers                 811008 bytes

Database mounted.
Database opened.
ORARAS> create table remedy.foo as select * from cdg.societa;

Table created.

Elapsed: 00:00:01.37
ORARAS> drop table remedy.foo;

Table dropped.

Elapsed: 00:00:01.99
ORARAS> alter system set filesystemio_options=asynch scope=spfile;

System altered.

Elapsed: 00:00:00.22
ORARAS> startup force
ORACLE instance started.

Total System Global Area 655854584 bytes

Fixed Size                   732152 bytes
Variable Size             318767104 bytes
Database Buffers          335544320 bytes
Redo Buffers                 811008 bytes

Database mounted.
Database opened.
ORARAS> create table remedy.foo as select * from cdg.societa;

Table created.

Elapsed: 00:00:00.84

-- 
Fabrizio Magni

fabrizio.magni_at_mycontinent.com

replace mycontinent with europe

Received on Thu Jun 23 2005 - 08:32:39 CDT