The IO team can use Oracle's IO requirements, apply whatever caching metric they wish, and also add any other IO-related metrics. While our utilization calculation has limited value, when comparing the theoretical worst-case utilization with the actual IO subsystem utilization, it will demonstrate the effectiveness of caching, changing IO subsystem capacity, and possibly various tuning efforts.

Suppose the IO administrator told you the IO subsystem has a capacity of 250 IOPS. Earlier, in the "Gathering IO Requirements" section, we calculated that, during the reporting interval, Oracle processes generate 5.59 IOPS. Once again, using the utilization formula, we have this calculation:

So, while the CPU subsystem is running at 100% utilization, if the IO subsystem is receiving only this specific Oracle instance's IO requests, and assuming there is no non-Oracle caching, the IO subsystem would be running at around 2.2% utilization. It appears the IO subsystem has plenty of capacity.