Re: DBWR pegged out

From: Kellyn Pedersen <kjped1313_at_yahoo.com>
Date: Tue, 8 Mar 2011 08:10:21 -0800 (PST)
Message-ID: <925201.89610.qm_at_web120204.mail.ne1.yahoo.com>

Can you offer us a little more information? Is this for one type of process? If it is from one type of process, have you traced it to see what is it truly waiting on? Are the waits due to the dbwr or is it simply i/o waits on your tempfiles?

I think we need more information on the actual waits to determine that you are looking at dbwr, as I'm not seeing that here...  

Kellyn Pedersen
Multi-Platform Database Administrator
www.pythian.com
http://www.linkedin.com/in/kellynpedersen http://dbakevlar.com  

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From: Doug Gernaat <dag_at_its.msstate.edu> To: oracle-l_at_freelists.org
Sent: Tue, March 8, 2011 8:55:04 AM
Subject: DBWR pegged out

after oracle suggested bumping up db_writer_processes from 2 to 4, at times it is still getting pegged out. "write complete waits" will become a top time event.
drilling down will show:

SID     User                            Wait state/time    Waiting Location
23     db_user               In waiting (2ms)     write complete waits, TEMP 
datafile:604
30     db_user               In waiting (88ms)    write complete waits, TEMP 
datafile:604
179     db_user               In waiting (101ms)    write complete waits, TEMP 
datafile:604
189     db_user               In waiting (0ms)     write complete waits, TEMP 
datafile:604
354     db_user               In waiting (109ms)    write complete waits, TEMP 
datafile:604
1532     db_user               In waiting (6ms)     write complete waits, TEMP 

datafile:604

and diff users will fall in out of these write complete waits. i always see TEMP... not any other dfiles.
also during these times... ora_ckpt will start blocking other sessions. is this I/O contention? any suggestions?

dbwr_io_slaves is set to 0.
this is 11.2.0.2 on solaris sparc 64.

thanks
-doug-

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http://www.freelists.org/webpage/oracle-l Received on Tue Mar 08 2011 - 10:10:21 CST