The I/O Activity tab on the Buffer Pools drilldown provides a summary of I/O activity involving the selected buffer pool. The graphs show rates for the following:
Reads and writes that use the buffer pool
Direct reads and writes, which do not go through the buffer pool, but access the database directly
The bottom of the tab lists average I/O times (in milliseconds) for both buffered and direct reads and writes. The average times are shown in milliseconds.
The graphs on the I/O Activity tab keep track of the rates for I/O activity that involves the buffer pool. These rates are plotted over consecutive monitoring intervals.
On the Databases drilldown, you might notice consistently high rates for the following activities on specific databases:
Physical read rates (compared to logical read rates)
Synchronous read or write rates
Direct I/O rates for a database
These high rates might be indications of performance degradation since the activities involve disk I/O and slow-downs in query processing. You can use the graphs on this I/O Activity tab to pinpoint those buffer pools that are not being used effectively to offset I/O on the database.