Re: oracle is causing high WIO

  • From: "Radoulov, Dimitre" <cichomitiko@xxxxxxxxx>
  • To: <raja4list@xxxxxxxxx>
  • Date: Mon, 24 Oct 2005 20:15:58 +0200

Sorry, my answer was about how to find witch processes are causing the high IO.

It's now that I read that you want to know "why oracle is causing this high WIO" ..., and it's a long story :)

Read Cary Millsap's How to Activate Extended SQL Trace (http://www.hotsos.com/e-library/abstract.php?id=29) and activate the extended sql trace for the processes you find with the command from the previous mail(prstat -m).




HTH
Dimitre Radoulov




----- Original Message ----- From: Radoulov, Dimitre
To: raja4list@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Sent: Monday, October 24, 2005 7:59 PM
Subject: Re: oracle is causing high WIO


Try prstat -m and check the major contributors for the % of SYS mode. I *think* the kernel mode includes the IO device wait time.

/app/oracle$ prstat -m
  PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/NLWP
11603 oracle    56 3.3 0.0 0.0 0.0 0.0  39 1.3  1K  73  1K   0 oracle/1
24601 oracle    11 3.6 0.0 0.0 0.0 0.0  86 0.0 160  17  6K   0 oracle/1
24599 oracle   6.2 4.1 0.0 0.0 0.0 0.0  90 0.0 138   5  5K   0 oracle/1



HTH,
Dimitre 

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