Based solely on the v$sysstat performance view, the IO subsystem is receiving read requests at nearly 530 MB/s. Oracle read requests (db file scattered read) are being satisfied in less than 1 ms, which indicates the Oracle blocks reside in the operating system buffer cache! While not shown in Figure 9-22, the average IO device utilization is around 2%, meaning they are idle.

The Oracle and application tuning strategies are intended to reduce the number of IO read calls, making an increase in IO activity and subsequent IO performance issues highly unlikely.

To summarize, by reducing both physical and logical block activity, performance can be significantly improved. This means SQL tuning and/or reducing SQL statement execution rates. Figure 9-23 shows there are three high-consuming physical IO SQL statements, with the top statement consuming more than twice as much physical IO as the second and third ones combined! Figure 9-24 shows the system is processing nearly 70 logical IOs each millisecond.