Average Number of I/O’s per Transaction
Hourly I/O’s per Transaction Graph.
The Average Number of I/Os per Transaction graph shows the average number of I/Os per
transaction for all users per hour. Both the total number of I/Os per transaction and the number of
synchronous I/Os per transaction are shown.
The Facts section of the graph displays the average transaction characteristics for the current
and previous two months. CPU time in seconds, average number of I/Os, and average number of
synchronous I/Os are shown.
A transaction must wait for a synchronous disk I/O to complete before it can continue processing.
On the other hand, a transaction can continue processing when an asynchronous I/O is
requested. As a result, even the asynchronous I/O may affect the transaction response time.
Transaction response times can increase over time if transactions require more synchronous I/O.
An increase in page fault rates can be a common cause of the increase in synchronous I/O. The
addition of logical views that require immediate maintenance of the view (an index) can be
another cause of the increase in synchronous I/O’s.
PM for Power Systems Graph Reference Document
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