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Friday, October 1, 2010

How to determine if I/O is the real issue from AWR report?




DB FILE SEQUENTIAL READ

=======================


'Wait Time` = 493 x 100% / 83.2% = 592.54 (s)

'Service Time' = 11023 (s)

'Response Time' = 11023 + 592.54 = 11615.54 (s)

If we now calculate percentages for all the 'Response Time' components:

CPU time = 94.8 %
db file sequential read = 4.24 %

control file sequential read = 0.16 %

control file parallel write = 0.1 %

db file parallel write = 0.07 %


Summary:


It is now obvious that the I/O-related Wait Events are not really a significant component of the overall Response Time and that subsequent tuning should be directed to the Service Time component i.e. CPU consumption.


HAPPY  LEARNING!

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