Gathering IO requirements is more complicated than gathering CPU requirements. Oracle9i Release 2 and earlier require querying from both v$sysstat and v$filestat, whereas later Oracle releases require querying only from v$sysstat. And depending on the information desired, different statistics are required. The following snippet shows the formulas for raw Oracle IO consumption (requirements) for Oracle9i Release.2 and earlier versions:

Figure 9-5 shows the instance statistics we need to calculate Oracle's IO consumption (its requirements) over Statspack's 149.97-minute interval. The only missing piece of information is the Oracle block size, which is needed to determine the MB/s figures. While not shown, the value is found in the Instance Parameter portion of any Statspack or AWR report. For this example, the db_block_size is 8192, which is 8KB.

Figure 9-5. Based on the same data as Figures 9-1, 9-2, and 9-3, shown are Oracle IO-related consumption (requirements) metrics. This is an Oracle Database 10g Release 2 system, so all the metrics can be gathered from the Instance Statistics section (based on v$sysstat), and then used to calculate read and write IO requirements for the server processes and background processes in both megabytes per second (MB/s) and IO operations per second (IOPS).