January 7, 2009 08:49pm pst

11.30.2008 at 03:38AM PST, ID: 23944783

	[x] Attachment Details

sar -d output clarification

[x]

The Solution Rating System

With so many solutions, how can you tell which solutions are most likely to help you and which ones are not? To provide you with a tool to use, we rate our solutions based on various elements that most accurately determine if a solution is a quality solution. To explain what factors affect the solution rating, here are the elements we take into consideration when formulating our solution rating.

The Grade of the Solution
The Zone Rank of the Expert Providing the Solution
The Number of Author and Expert Comments
The Number of Experts Contributing
The Feedback of the Community

Your Input Matters
Because of the way the system is set up, the most important variable in this equation is you. As a member of Experts Exchange, you are able to cast your vote on the quality of the solutions in regard to how complete, accurate, helpful and easy to understand each solution is. When you provide your feedback, each rating is adjusted accordingly. So, if you see a solution that has a poor rating that you think is a good solution, let us know by rating it. As you do, the rating will be adjusted and will become more accurate for other members of our site.

If you have any suggestions that you would like to make for our rating system, please ask a question in the Suggestions Zone of Community Support.

Thank you!

9.3

Zones:

Computer Hard Drives, Unix Operating Systems, Oracle HCM

Tags:

sar -d and oracle wait time

I have an Oracle query which does more than three million database block reads(.This is the number of physical reads).
Now , I ran the query in two different time intervals. say Internal 1 and interval 2.
I got a huge difference in the query excution time. When I examined AWR report from Oracle the following are the observations.
1) Both the times number of actual disk reads were almost same.
2) The AWR statistics event "DB file Sequential read" showed an average of "0ms" for interval 1 and "2ms" for interval 2.
3) "time for User IO "is the component increased for the second execution.

I am aware of the following things.
1) 2 ms is an excellent service time from OS perspective.
2) There are several factors (like load etc..) influencing the average service/wait time.

Having said all these what I try to uderstand is, from the attached sar -d output for the two different intervals can I conclude that.
"it is the averge wait time increase caused the oracle's average readtime to increase to 2ms."?

(when I talk about 3 million IOs an increase 2ms per IO can cuase significant change)

Based on any of the other OS stats info available in these sar output can we rule out or confirm the above statement?

         
           
             1:
2:
3:
4:
5:
6:
7:
8:
9:
10:
11:
12:
13:
14:
15:
16:
17:
18:
19:
20:
21:
22:
23:
24:
25:
26:
27:
28:
29:
30:
31:
32:
33:
34:
35:
36:
37:
38:
39:
40:
41:
42:
43:
44:
45:
46:
47:
48:
49:
50:
51:
52:
53:
54:
55:
56:
57:
58:
59:
60:
61:
62:
63:

           
           
             ==========================INTERVAL(1) =================================
 
18:30:00
         c10t10d4    2.28    0.50      16     815    0.00    3.08
         c10t10d5    3.59    0.50      22    1193    0.01    4.03
         c10t13d6    5.51    0.50      48    2589    0.00    2.77
         c10t13d7    1.81    0.51      13     649    0.02    3.32
         c10t14d4    0.93    0.50       7     349    0.00    2.33
         c10t14d5    0.71    0.50       4     213    0.00    2.40
         c10t14d6    2.07    0.50      17     898    0.00    2.76
           c6t3d2    0.00    0.50       0       0    0.00    0.41
18:40:00
         c10t10d4   10.97    0.50      60    2604    0.00    3.45
         c10t10d5   12.90    0.50      62    2762    0.00    3.63
         c10t13d6   19.33    0.50     111    5319    0.00    3.12
         c10t13d7    6.60    0.53      33    1491    0.05    3.33
         c10t14d4    3.00    0.50      17     761    0.00    3.23
         c10t14d5    2.71    0.50      13     540    0.00    2.80
         c10t14d6    9.06    0.50      47    2143    0.01    3.33
           c6t3d2    0.00    0.50       0       0    0.00    0.28
18:50:01
         c10t10d4    6.97    0.50      54    2792    0.00    2.31
         c10t10d5   12.83    0.50      88    4003    0.00    2.42
         c10t13d6   16.59    0.50     140    6816    0.00    2.07
         c10t13d7    6.37    0.50      53    2187    0.01    1.94
         c10t14d4    2.50    0.50      22    1150    0.00    1.86
         c10t14d5    2.80    0.50      15     825    0.00    2.58
         c10t14d6    7.35    0.50      69    3249    0.01    1.81
       
       
       
 
===========================INTERVAL 2 =================================
 
05:10:00
         c10t10d4   28.20    0.51     120    5791    0.03    4.53
         c10t10d5   35.20    0.51     133    6869    0.03    4.92
         c10t13d6   30.44    0.51     126    4892    0.03    4.42
         c10t13d7   17.38    0.51      69    2708    0.02    4.04
         c10t14d4   27.40    0.50      80    5690    0.01    5.85
         c10t14d5   24.97    0.51      86    3205    0.01    4.35
         c10t14d6   12.17    0.51      49    2008    0.02    4.03
           c6t3d2    0.05    0.50       0      21    0.00    1.87
05:20:00
         c10t10d4   25.18    0.53     128    7781    0.05    4.04
         c10t10d5   33.02    0.54     173   10804    0.06    4.14
         c10t13d6   39.09    0.57     239   13952    0.09    3.98
         c10t13d7   10.12    0.53      56    2895    0.04    3.64
         c10t14d4   21.56    0.52      95    5348    0.02    4.01
         c10t14d5   10.57    0.51      49    2695    0.01    3.84
         c10t14d6   28.86    0.53     139    8328    0.05    3.97
           c6t3d2    0.00    0.50       0       0    0.00    0.55
05:30:00
         c10t10d4   27.12    0.52     115    6827    0.04    4.62
         c10t10d5   35.47    0.52     150    9147    0.03    4.36
         c10t13d6   39.99    0.52     198   11033    0.04    3.95
         c10t13d7   21.76    0.50      94    5089    0.01    3.42
         c10t14d4   21.26    0.50      75    4199    0.01    4.92
         c10t14d5   21.01    0.50      87    3889    0.01    3.69
         c10t14d6   15.28    0.51      69    3340    0.01    3.51
           c6t3d2    0.00    0.50       0       0    0.00    0.63
           
=========================== end of INTERVAL 2 =================================

           
         

Attachments:

sar-comparison.txt (3 KB) (File Type Details)

sar output for interval 1 and interval 2

#	Title
1	Observations of 9/11
2	Request for clarification from patrickab
3	Observer Pattern in Java
4	Timed Statistics performance influence
5	Observation. How is observation defi…
6	Fantasy Basketball statistics