IBM 990 - Manual (Page 179)

Chapter 7. Sysplex functions 167
CPs are Processor Units used to process z/OS, OS/390, CFCC, z/VM, Linux, TPF, VSE/ESA,
or z/VSE instructions. The logical partition can use dedicated
or shared CPs. However, it is
not possible to have a logical partition with dedicated and shared CPs at the same time.
ICFs are PUs dedicated to process the CF Control Code (CFCC) on a Coupling Facility
image, which is always running on a logical partition. A CF image can use dedicated
and/or
shared ICFs. It can also use dedicated or shared CPs. With Dynamic ICF Expansion, a
Coupling Facility image can also use dedicated ICFs and shared CPs.
The z990 can have ICF processors defined to CF Images.
A z990 server Coupling Facility image can have one of the following defined in the image
profile:
Dedicated ICFs
Shared ICFs
Dedicated
and shared ICFs
Dedicated CPs
Shared CPs
Dedicated ICFs
and shared CPs
Shared ICFs add flexibility. However, running with shared Coupling Facility Processor Units
(ICFs or CPs) adds overhead to the coupling environment and is not a recommended
production configuration.
In Figure 7-4, the server on the left has two environments defined (Production and Test), each
having one z/OS and one Coupling Facility image. The Coupling Facility images are sharing
the same ICF processor. The logical partition Processing Weights are used to define how
much processor capacity each Coupling Facility image can have. The
Capped option can also
be set for the Test Coupling Facility Image, to protect the production environment.
Connections between these z/OS and Coupling Facility images can use IC channels to avoid
the use of real (external) coupling channels and to get the best link bandwidth available.
Figure 7-4 z990 ICF options - Shared ICFs
z/OS
Prod
z/OS
Prod
Function Setup
HMC
z990
Partition
Image
Profile
ICF CP
CF CF
Test Sysplex
z/OS
Test z/OS
Test CF