HCD and the coupling facility

HCD provides the user interface to support processors that have coupling facility capability.

The coupling facility itself is implemented as an extension to PR/SM features on selected processors (refer to z/OS HCD Planningz/OS HCD Planning for a list) and runs in a PR/SM partition. It enables direct communication between processors through a specific communication partition (coupling facility partition), connected by coupling facility channels.

You use HCD to specify whether a logical partition is running a coupling facility or an operating system. New channel path definitions in the IODF are used to connect a coupling facility-capable processor to a coupling facility partition:

• The coupling facility receiver channel (CFR channel) path that accesses the partition the coupling facility is running on.
• The coupling facility sender channel (CFS channel) path that accesses the partition the operating system is running on.
• The coupling facility peer channel path that accesses either partition bidirectionally on IBM zSeries processors or their successors.

HCD automatically generates the coupling facility (CF) control unit and devices that are necessary for IOCP processing. Figure 7 shows a processor configuration with coupling facility implemented.

Figure 7. Processor configuration with coupling facility implemented

HCD enables you to dynamically reconfigure the coupling facility channels that are connected to the operating system partition.

For more information on HCD and coupling facility, refer to z/OS Parallel Sysplex Overviewz/OS Parallel Sysplex Overview.