Re: "log file parallel write" wait times get increased a lot after upgrading from 10203 to 10204

From: Tanel Poder <tanel_at_poderc.com>
Date: Wed, 1 Dec 2010 00:31:19 +0000
Message-ID: <AANLkTimhdDV+z1MXVjHU1qybjO4tqnULj=AR0iG8E1ob_at_mail.gmail.com>

It's more likely that you hit an instrumentation bug which didn't record any log file parallel write wait events (in most cases) in 10.2.0.3 and the bug was fixed in 10.2.0.4. I don't know the bug# but I've seen the same issue, also for db file parallel writes.

So you're not waiting more, you just know about this waiting now. Having only 1193 log file parallel writes per day in a busy system doesn't sound correct anyway...

--
Tanel Poder
http://tech.e2sn.com
http://blog.tanelpoder.com



On Tue, Nov 30, 2010 at 7:07 AM, Eagle Fan <eagle.f_at_gmail.com> wrote:



> hi:

>

> I noticed that after upgraded from 10203 to 10204, the number of waits of

> parallel write got increased a lot.

>

> We are using lgwr async IO (_lgwr_async_io=true and disk_asynch_io=true).

> OS is Solaris 10.

>

> SNAP_TIME         TOTAL_WAITS TIME_WAITED

>

> ----------------- ----------- -----------

>

> 20100425 00:00:00        1193          20

>

> 20100426 00:00:00        1187          19

>

> 20100427 00:00:00    83753743     3122627  -- after upgraded from 10203 to

> 10204

>

> 20100428 00:00:00    94783396     3353594

>

> 20100429 00:00:00    96792543     3320591

>

> 20100430 00:00:00    98197875     3245199

>

> 20100501 00:00:00    98144618     3162137

>

> I checked several databases, all of them had the same behavior.

>

> I tried to find some docs to explain this on metalink, but I didn't find

> anything.

>

> Did anybody also have such change before? What's the reason behind this?

>

> And I'm curious what the result is if _lgwr_async_io is false.

>

> Thanks in advance.

>

> --

> Eagle Fan (www.dbafan.com)

>


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Received on Tue Nov 30 2010 - 18:31:19 CST