VirtaThon 2011 - Mining the AWR
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Mining the AWR repository for Capacity Planning, Visualization, & other real world stuff
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Transcript of VirtaThon 2011 - Mining the AWR
Mining the AWR repository for Capacity Planning, Visualization,
& other real world stuff
Who am I?
• Karl Arao, Oracle ACE, OCP‐DBA, RHCE• Currently @ Enkitec ‐ Senior Technical Consultant • Formerly @ SQL*Wizard ‐ Solutions Architect• Blog: http://karlarao.wordpress.com• Wiki: http://karlarao.tiddlyspot.com• Twitter: http://twitter.com/karlarao
What will I talk about?
Overwhelming
DBA_HIST_* views
My first close encounter
gc block lost – sudden slow down
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost
gc block lost – sudden slow down
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost
gc block lost – sudden slow down
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost
gc block lost – sudden slow down
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost
After gc block lost – normal workload
http://karlarao.wordpress.com/2009/06/07/diagnosing-and-resolving-gc-block-lost
Utilization = Requirement / Capacity
Double Y Axis Graph
t1 ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐> t0335 – 336 – 337 – 338 – 339
delta issue
AWR Scripts
Visualization
Can’t go back in time?
AAS – Average Active SessionsKyle Hailey: http://www.perfvision.com/ftp/class/02_AAS.ppt
Max CPU
Max CPU
AAS – the Golden MetricAAS & CPU count as a yardstick for a possible performance problem:if AAS < 1 ‐‐ Database is not blockedAAS ~= 0 ‐‐ Database basically idle‐‐ Problems are in the APP not DBAAS < # of CPUs‐‐ CPU available‐‐ Database is probably not blocked‐‐ Are any single sessions 100% active?AAS > # of CPUs‐‐ Could have performance problemsAAS >> # of CPUS‐‐ There is a bottleneck
AAS from V$ACTIVE_SESSION_HISTORYAAS = Sample Count / Elapsed Time
= 19410 / 600= 32.35
CPU count = 4
AAS from DBA_HIST_ACTIVE_SESS_HISTORYAAS = (Sample Count * 10) / Elapsed Time
= (1950 * 10) / 600= 32.5
CPU count = 4
AAS from AWR ReportAAS = DB Time / Elapsed Time
= 291.81 / 9.10= 32.07
CPU count = 4
AAS from AWR Top EventsAAS = DB Time / Elapsed Time
291.81 / 9.10 = 32.07
AAS = Event Time / Elapsed Time17410 / 546 = 31.9
CPU count = 4
awr_topevents.sql
Textual trends
AAS throughout the AWR retention period!
http://karlarao.wordpress.com/2010/07/25/graphing-the-aas-with-perfsheet-a-la-enterprise-manager
Capacity Planning
Utilization is the ultimate metric!
awr_genwl.sql
http://karlarao.wordpress.com/2010/01/31/workload-characterization-using-dba_hist-tables-and-ksar
U = R / C
where aas > 1
Filter the data points• AAS range
aas > 1
• Per SNAP_ID or range of SNAP_IDsid in (336)where id >= 336 and id <= 340
• Oracle CPU Utilizationoracpupct > 50
• OS CPU Utilizationoscpupct > 50
• Workload periods
AND TO_CHAR(s0.END_INTERVAL_TIME,'D') >= 1 ‐‐ Day of week: 1=Sunday 7=SaturdayAND TO_CHAR(s0.END_INTERVAL_TIME,'D') <= 7AND TO_CHAR(s0.END_INTERVAL_TIME,'HH24MI') >= 0900 ‐‐ HourAND TO_CHAR(s0.END_INTERVAL_TIME,'HH24MI') <= 1800AND s0.END_INTERVAL_TIME >= TO_DATE('2010‐jan‐17 00:00:00','yyyy‐mon‐dd hh24:mi:ss') ‐‐ Data rangeAND s0.END_INTERVAL_TIME <= TO_DATE('2010‐aug‐22 23:59:59','yyyy‐mon‐dd hh24:mi:ss‘)
core need = # of cores * utilization * 1.25Database Consolidation Best Practices
http://husnusensoy.files.wordpress.com/2010/05/database‐consolidation‐best‐practices.pdf
Total disk IOPS = (IOPS * Read Ratio) + (IOPS * Write Ratio * RAID penalty)
Number of disk = Total disk IOPS / IOPS per disk
awr_iowl.sql
Average latency issue
60 minutes interval 10 minutes interval
latency (ms) = (readtim / phy reads) * 10
Linear Regression
x data (CPU) = is the "independent value", used to predict the value of y
y data (AAS) = is the "dependent value", variable whose value is to be predicted
r2toolkit
Uses the following inbuilt Oracle functions:
•regr_count•regr_r2•regr_intercept•regr_slope
r2toolkit
Linear Regression – what’s the value?
Linear Regression on 2 node RAChttp://karlarao.tiddlyspot.com/#r2project
racnode1 racnode2
Drilling down on the peak workload... with AAS of 10
Drilling down on the peak workload... with AAS of 10
Now on the low workload period... with AAS of 2.2
Now on the low workload period... with AAS of 2.2
Recap
• Mine the beautiful data set
• Visualization tell a story immediately
• Statistics to make sense of data
Let the AWR data set
change your mind set!
Thank you!
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 Consolidationhttp://resources.orapub.com/product_p/server_consolidation_ppt.htm
• Husnu Sensoy @ husnusensoy.wordpress.com – Database Consolidation Best Practiceshttp://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
