zHPF support in z/VSE 6.2
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One of the hardware exploitation items introduced with z/VSE 6.2 is the High Performance FICON for z Systems (zHPF) support. In April 2017 I posted already a blog entry about this topic.
The zHPF channel Input/Output (I/O) architecture can improve the execution of small block I/O requests. z/VSE translates applicable I/O commands into the zHPF protocol and thus transparently exploit the zHPF protocol for user applications. No adaptation is required. Multiple channels commands are sent as a single entity to the control unit. That is the channel forwards a chain of commands and has no longer to keep track of each single CCW (Channel Command Word). This may lead to reduced overhead and increases the I/O rate on a channel. The performance benefits depend on your workload. zHPF support is provided for ECKD channel commands.
A few implementation details:
The SYSDEF SYSTEM command is extended by a new zHPF parameter. After IPL completed you can start the zHPF support via SYSDEF SYSTEM,ZHPF=START. You may stop the zHPF support via SYSDEF SYSTEM,ZHPF=STOP, and restart it any time. So you can easily verify, if your workload can benefit from z/VSE's zHPF support. I/O timings can be verified via the SIR SMF command.
More details are in the z/VSE Administration book. You can download it from the PDF library - here.