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

The default for _lgwr_async_io = false, right?   At least it is in my database.

It is a hidden parameter, so was it changed in 10203?  Perhaps ...   Not sure 
how much documentation there is on these parameters, but might be inclined to 
believe that because they are hidden there is a shortage of documentation.




Joel Patterson
Database Administrator
904 727-2546

________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On 
Behalf Of Eagle Fan
Sent: Tuesday, November 30, 2010 2:07 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: "log file parallel write" wait times get increased a lot after 
upgrading from 10203 to 10204

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<http://www.dbafan.com>)

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