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)
db file sequential read = 4.24 %
control file sequential read = 0.16 %
control file parallel write = 0.1 %
db file parallel write = 0.07 %
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.