Zhpf channel programming

2020-02-21 18:36

The IOSZHPF macro provides information about the zHPF capabilities of a device from the operating system, processor, channel, and device point of view. The information returned is mapped by IOSDZHPF and reflects the minimum capability of all of the online channels for a device.The channel program contains the instructions used by the channel subsystem and the device to execute an IO operation. This section describes what you need to consider when you create a channel program for an EXCP request. zhpf channel programming

zHPF enabled device. There are no messages on the console, but many logrec ICYTRACE records for the DB2 DBM1 address space. Turning off zHPF is an option disable zHPF on LPARS running DB2 via the MVS command SETIOS ZHPFNO There is no data loss because Media Manager will redrive the IO with a nonzHPF channel program.

An IOS000I message is issued on a failed zHPF channel program that is being used for a device that: is enabled for zHPF (See UCBFCX b'1 which Indicates that zHPF is supported for this device). the device is NOT enabled for zHPF phase 1 channel programs. You might get a WARNING message if your device does not support zHPF when using SAS 9. 4 TS1M3 with the hot fix from SAS Note applied or SAS 9. 4 TS1M4 and later releases. zhpf channel programming Figure 1. zHPF channel program The parts of a zHPF channel program include: A transport control word (TCW) that contains pointers to all of the other areas of the channel program and the number of bytes to be read or written.

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