1. Oracle Closed World 2010:
Graphing the AAS ala EM + doing
some cool linear regression

2. Who am I?
• Karl Arao, Oracle ACE, OCP‐DBA, RHCT
• Solutions Architect / Principal Consultant @ SQL*Wizard
• Blog: http://karlarao.wordpress.com
• Wiki: http://karlarao.tiddlyspot.com

3. DBA_HIST_* tables

4. My first close encounter

5. gc block lost
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost

6. AWR Scripts

7. Visualization

8. Can’t go back in time?

9. AAS – Average Active Sessions
Kyle Hailey: http://www.perfvision.com/ftp/emea_2010_may/02_AAS.ppt
Max CPU
Max CPU

10. AAS – the Golden Metric
AAS & CPU count as a yardstick for a possible performance problem (I suggest reading Kyle's
stuff about this):
if AAS < 1
‐‐ Database is not blocked
AAS ~= 0
‐‐ Database basically idle
‐‐ Problems are in the APP not DB
AAS < # of CPUs
‐‐ CPU available
‐‐ Database is probably not blocked
‐‐ Are any single sessions 100% active?
AAS > # of CPUs
‐‐ Could have performance problems
AAS >> # of CPUS
‐‐ There is a bottleneck

11. awr_topevents.sql

12. Textual trends

16. AAS throughout the AWR retention
period!
http://karlarao.wordpress.com/2010/07/25/graphing-the-aas-with-perfsheet-a-la-enterprise-manager

17. Capacity Planning

18. awr_genwl.sql

19. http://karlarao.wordpress.com/2010/01/31/workload-characterization-using-dba_hist-tables-and-ksar

20. U = R / C

21. where aas > 1

22. Filter the data points
• AAS range
aas > 1
• Per SNAP_ID or range of SNAP_IDs
id in (336)
where id >= 336 and id <= 340
• Oracle CPU Utilization
oracpupct > 50
• OS CPU Utilization
oscpupct > 50
• Workload periods
AND TO_CHAR(s0.END_INTERVAL_TIME,'D') >= 1 ‐‐ Day of week: 1=Sunday 7=Saturday
AND TO_CHAR(s0.END_INTERVAL_TIME,'D') <= 7
AND TO_CHAR(s0.END_INTERVAL_TIME,'HH24MI') >= 0900 ‐‐ Hour
AND TO_CHAR(s0.END_INTERVAL_TIME,'HH24MI') <= 1800
AND s0.END_INTERVAL_TIME >= TO_DATE('2010‐jan‐17 00:00:00','yyyy‐mon‐dd hh24:mi:ss') ‐‐ Data range
AND s0.END_INTERVAL_TIME <= TO_DATE('2010‐aug‐22 23:59:59','yyyy‐mon‐dd hh24:mi:ss‘)

24. Straight line graph: Slope‐Intercept Form
y = mx + b

25. AAS vs. CPU% utilization
http://karlarao.tiddlyspot.com/#r2project

33. “oracpupct” column also has a good linear fit. Since the
server’s load is CPU centric (see top r2 stats from .92 and
above), why not use it?
AAS(y) against CPU% Utilization(x) will be more
meaningful/readable instead of “CPU used by this session”

34. AAS vs. CPU% utilization
http://karlarao.tiddlyspot.com/#r2project

35. Drilling down on the peak workload...
with AAS of 10

36. AAS vs. CPU% utilization
http://karlarao.tiddlyspot.com/#r2project

41. Now on the low workload period...
with AAS of 2.2

42. AAS vs. CPU% utilization
http://karlarao.tiddlyspot.com/#r2project

46. Conclusion

47. References and Tools
• http://karlarao.wordpress.com
– http://karlarao.tiddlyspot.com/#%5B%5BStorage%20IOPS%2Ccapacity%2Cperformance
%2Ccost%5D%5D
– http://karlarao.tiddlyspot.com/#Statistics
– http://karlarao.tiddlyspot.com/#OraclePerformance
• Tanel Poder @ http://blog.tanelpoder.com
– http://www.tanelpoder.com/files/TPT_public.zip
– http://www.tanelpoder.com/files/PerfSheet.zip
– Neil Gunther & Tanel Poder ‐ Multidimensional Visualization of Oracle Performance
using Barry007 http://arxiv.org/pdf/0809.2532
• Kyle Hailey @ http://ashmasters.com , http://www.perfvision.com
• Craig Shallahamer @ orapub.com
– Introduction To Oracle Server Consolidation
http://resources.orapub.com/product_p/server_consolidation_ppt.htm
• Husnu Sensoy @ husnusensoy.wordpress.com
– Database Consolidation Best Practices
http://husnusensoy.files.wordpress.com/2010/05/database‐consolidation‐best‐
practices.pdf
• Andy Rivenes @ http://www.appsdba.com/pubs.htm
• Neeraj Bhatia @ www.nioug.org/files/Linear_Regression.pdf

48. Contact me through:
karao@sqlwizard.com