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Re: 10G and UFS - long write times

From: Riyaj Shamsudeen <>
Date: Thu, 08 Jun 2006 08:41:19 -0500
Message-ID: <>

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    Michael McMullen hit the point here, precisely.

    >>We are seeing big problems when issuing disk writes using 10G (both 10.1 and 10.2).

    What tool did you use to see the write response time ? Did you trace DBWR or LGWR to see the write response time and IO related waits ? Assuming unix, does iostat indicates worse average response time for those devices ?

    >>The test is very simple and quick to do     And potentially misleading too. This test case is proving that having very high commit frequency will introduce additional performance issues.

    If you want to understand why why your code is slower, turn on SQLtrace in 9i and in 10g for your test case. Then find where that extra time is spent. Also, compare session statistics between 9i and 10g. That will tell you where to concentrate. Further, log file sync and log buffer waits are not just IO related. You might want to decrease your commit frequency to eliminate these events from the equation too.

    There are so many different optimization techniques introduced in 10g, your test case might be probing the vulnerability of a feature.

Riyaj Shamsudeen

****Michael McMullen wrote:
> I understand that there is a severe difference in timings. But is it right
> to test fundamentally bad code? I've been testing 10g on a Sun T2000, both
> on the san and local disks. I never could get it as fast as my 8i/9i
> installations on other servers. Granted, I was not comparing apples and
> oranges. I had to give it back before I could bring 9i on the T2000 to test.
> But my initial reaction with 10g is it just didn't seem as forgiving as
> other versions of oracle.
> How about testing a big import with lots of parallel index creation?
> --



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Received on Thu Jun 08 2006 - 08:41:19 CDT

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