As shown in Figure 3-25, a 40% elapsed time reduction was observed by using zHyperWrite,  which resulted in a 22% overall transaction response time improvement. A minor CPU increase was observed in the Db2 MSTR address space to trigger the extra  I/Os using zHyperWrite. The SRB time in MSTR address space is zIIP eligible starting with  Db2 11. In some cases, another indirect benefit of zHyperWrite can be observed. The reduced log  write wait time (from zHyperWrite) can lead to reductions in other types of contentions, which  in turn can result in more CPU time savings because Db2 has fewer contentions  (suspend/resume activities) to manage. VSAM data set striping for Db2 active log data sets were commonly used to improve the  throughput processing that triggers heavy update activity. With significant improvement in  disk subsystem technology, some of the bottlenecks that were seen in log write I/Os shifted  and in those cases, the use of active log striping does not add any benefit. Should you strip the active log data sets? Because many factors influence whether it is  beneficial to stripe the active log, a simple answer to this question is no longer available. In this section, we describe the basic process that is used in log striping and the results from  measurements that were taken in a controlled environment at the Silicon Valley Lab. Note:  This section is not meant to be a comprehensive study of active log striping. For  example, the environment that we used did not include synchronous disk mirroring  (Peer-to-Peer Remote Copy). Our intention is to demonstrate some of the factors and  considerations that influence the performance of active log striping. Chapter 3. Synergy with the IBM Z platform  123 3.9 Active log data set striping  Figure 3-25 zHyperWrite performance 