IBM Z9, Planning Manual

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Coupling Facility Planning Considerations
The coupling facility provides shared storage and shared storage management
functions for the sysplex (for example, high speed caching, list processing, and
locking functions). Applications running on z/OS images in the sysplex define the
shared structures used in the coupling facility.
The coupling facility allows applications, running on multiple z/OS images that are
configured in a sysplex, to efficiently share data so that a transaction processing
workload can be processed in parallel across the sysplex.
PR/SM LPAR allows you to define the coupling facility, which is a special logical
partition (LP) that runs coupling facility control code. Coupling facility control code is
Licensed Internal Code (LIC).
At LP activation, coupling facility control code automatically loads into the coupling
facility LP from the support element hard disk. No initial program load (IPL) of an
operating system is necessary or supported in the coupling facility LP.
Coupling facility control code runs in the coupling facility LP with minimal operator
intervention. Operator activity is confined to the Operating System Messages task.
PR/SM LPAR limits the hardware operator controls usually available for LPs to
avoid unnecessary operator activity.
Coupling facility channel hardware provides the connectivity required for data
sharing between the coupling facility and the CPCs directly attached to it. Coupling
facility channels are point-to-point connections that require a unique channel
definition at each end of the channel. See “Coupling Facility Channels” on page
2-54.
Test or Migration Coupling Configuration
You can run a test or migration coupling facility to test and develop data sharing
applications. You can define a test or migration coupling facility LP on the same
CPC where other LPs are:
v
Running z/OS images connected to the coupling facility
v
Running noncoupled production work
A single CPC configuration has the following considerations:
v Simultaneous loss of the coupling facility and any z/OS images coupled to it (a
more likely possibility in a single CPC configuration) can potentially cause
extended recovery times
You can define a test or migration coupling facility with or without coupling facility
channel hardware. See “Defining Internal Coupling Channels (TYPE=ICP)” on page
2-58 for information on how to define a test or migration facility without coupling
facility channel hardware.
CFCC Enhanced Patch Apply
With the CFCC Enhanced Patch Apply, you can perform a disruptive install of new
CFCC code on a test CF and run it, while a production CF image in the same CEC
remains at the base CFCC code level. Then when the test CF is successful, the
new CFCC code can be installed on the production CF. Both installs can be done
without a Power On Reset (POR) of the CEC.
Chapter 2. Planning Considerations
2-39