As Figure 9-27 shows and as we expected, physical IO has been virtually eliminated. The total service time has also decreased. We were hoping for a 30% drop in total response time. But when comparing the Oracle analysis shown in Figure 9-21 to Figure 9-27, we can see the total response time decreased from 2,644 seconds to 1,257 seconds, which is a 52% improvement! (A direct comparison was possible because the collection interval was the same: 30 minutes.) The large drop in service time is due to less cache management related to placing blocks into the buffer cache. The decrease in Oracle's CPU consumption should result in a drop in CPU utilization. Any further performance gain should now focus on reducing CPU consumption, which is squarely focused on heavy logical IO SQL.

Figure 9-27. Shown is the 30-minute interval ORTA as a result of the buffer cache increase. Comparing this to Figure 9-21, as expected, total queue time has been virtually eliminated. Total service time has also decreased due to less buffer cache management related to placing buffers into the cache.

Figure 9-28 shows the operating system is looking even better than before! The CPU utilization dropped from 28% to 20%, and the IO subsystem is receiving from Oracle less than 1 MB/s in read and writes. So, it appears that increasing the Oracle buffer cache has had a very positive effect on resource consumption.