RE: wio above 20% - is that high?

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Thu, 2 Dec 2004 08:35:01 -0600
Message-ID: <006d01c4d87c$1b0bd0c0$6400a8c0@CVMLAP02>

Susan,

One way I'd encourage you to think about your question is to ask:

Is there *any* circumstance under which a really high value might be acceptable (or perhaps even desirable)?
Is there *any* circumstance under which a really low value might be unacceptable?

I haven't thought your particular question through to the end, but in my experience, every time I've ever analyzed a question of your question's format in this way, I've discovered that there is NO threshold that can = be
counted upon to indicate even the presence or absence of a problem. When = you
can't even reliably tell whether there *is* a problem or not, then you certainly can't use the metric to measure anything about *how* good or = bad a
problem might be. I've found every system-wide utilization metric I've = ever
analyzed to lead me to the same dead end (including the database buffer cache hit ratio, various latch miss ratios, the %sys CPU ratio, various = I/O
rates, index vs full-scan break-even ratios, even system-wide average response time).

Every time I've done the analysis I'm suggesting, I've found the same conclusion: stop looking at derivative metrics like system-wide = utilization
rates, and start looking at what really matters: response times of individual, prioritized business tasks.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

Upcoming events:
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Visit www.hotsos.com for schedule details...

-----Original Message-----
From: oracle-l-bounce_at_freelists.org =
[mailto:oracle-l-bounce_at_freelists.org]
On Behalf Of susan lam
Sent: Thursday, December 02, 2004 7:32 AM To: oracle-l_at_freelists.org
Subject: wio above 20% - is that high?

Is the wio below considered too high? One of the folks here thinks that as long as there are ample CPU %idle, it's fine. I think that wio is fine if it remains in the single digit or spikes occasionally but not prolong over a long period of time which in my case - over 20mins. Also, I think because of the high wio, the %usr remains low.=20

Any thoughts?

thanks.

susan=20

16:28:06    %usr    %sys    %wio   %idle
16:28:10       3       3      22      71
16:28:14       2       2      15      80
16:28:18       2       3      15      80
16:28:22       3       4      20      73
16:28:26       2       4      17      77
16:28:30       3       4      22      71
16:28:34       2       3      17      78
16:28:38       2       3      20      75
16:28:42       4      22      14      60
16:28:46       1      26      11      61
16:28:50       2      28      17      52
16:28:54       4      24      18      54
16:28:58       3      26      22      48
16:29:02      15      10      24      51
16:29:06      12       6      24      60
16:29:10      11       4      18      67
16:29:14       3       4      22      71
16:29:18       2       4      19      75
16:29:22       2       3      17      78
16:29:26       4       6      21      70
16:29:30       2       4      17      76
16:29:34       2       3      18      77
16:29:38       3       4      11      82
16:29:42       2       2      18      79
16:29:46       2       3      17      78
16:29:50       2       3      22      74
16:29:54       3       4      20      74
16:29:58       2       4      16      78
16:30:02       4       5      20      72
16:30:06       2       2      15      80
16:30:10       2       3      13      83
16:30:14       4       4      22      70
16:30:18       3       4      22      71
16:30:22       1       2      12      84
16:30:26       3       4      20      73
16:30:30       2       4      24      70
16:30:34       2       4      15      79
16:30:38       2       3      12      83
16:30:42       2       3      11      84
16:30:46       1       2      16      82
16:30:50       3       5      22      71



	=09
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Received on Thu Dec 02 2004 - 08:34:52 CST