Overview of zHPF Support

High Performance FICON (zHPF) is a channel I/O architecture that is designed to improve the execution of small block I/O requests. By using a Transport Control Word (TCW) the zHPF support facilitates the processing of an I/O request by the channel and the control unit. I/O operations that use TCWs are defined to be run in transport mode. A conversion routine translates a command mode channel program into a transport mode channel program. This makes zHPF support transparent for user applications.

The TCW enables multiple channel commands to be sent to the control unit as a single entity. The channel forwards a chain of commands and does not need to keep track of each single CCW. This leads to cost reduction and increases the maximum I/O rate on a channel. The performance improvement depends on your workload.