IBM Z9, Planning Manual

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For a test configuration only, if this option is not available and coupling facility LPs
must share a general purpose CP with non-CF workloads, diligent adherence to the
preceding recommendations for coupling facilities using shared CPs will minimize
undesirable consequences.
For greater detail on how to plan for and set-up a parallel sysplex in a shared CP
environment, please see one or more of the following:
Dynamic ICF Expansion (http://www.ibm.com/support/techdocs/atsmastr.nsf/
PubAllNum/W98028)
MVS/ESA
™
Parallel Sysplex Performance (http://www.ibm.com/support/
techdocs/atsmastr.nsf/PubAllNum/W9731A)
MVS/ESA Parallel Sysplex Performance - LPAR Performance
Considerations for Parallel Sysplex Environments (http://www.ibm.com/
support/techdocs/atsmastr.nsf/PubAllNum/W9609)
Coupling Facility LPs Using Dynamic ICF Expansion
Important Note
Dynamic ICF Expansion and Enhanced Dynamic ICF Expansion across ICFs
is not recommended for coupling facilities that are used for primary production
workload. All processors assigned to the coupling facility partition should be
dedicated to that logical partition if it is used used for primary production
workload.
Using dedicated ICF CPs and shared general purpose CPs for coupling facility LPs
has the following considerations:
v
The dedicated ICF CPs have the same considerations as listed earlier under
“Coupling Facility LPs using dedicated Central Processors (CPs) or Dedicated
Internal Coupling Facility (ICF) CPs”.
v RMF reports the data for a dynamic ICF expansion partition on two lines; one
line to report the dedicated ICF CPs and a second line to report the shared
general purpose or shared ICF CPs.
v
The processing weight specified for a coupling facility LP using dynamic ICF
expansion functions very much the same as with a logical partition using only
shared CPs. The only difference is the processing weight is divided among the
shared general purpose or shared ICF CPs in the coupling facility rather than all
the CPs in the logical partition.
v
You should not cap the processing weight for a coupling facility LP using
dynamic ICF expansion. If you do, LPAR attempts to support the cap but may not
be successful and the system can be less responsive.
v All shared general purpose or shared ICF CPs of a dynamic ICF expansion
coupling facility LP will use dynamic coupling facility dispatching on those shared
CPs for their dispatching. The DYNDISP coupling facility command cannot be
issued for a dynamic ICF expansion coupling facility. The value will be forced ON
in this configuration.
v
Each shared general purpose or shared ICF CPs defined and online in a
coupling facility LP using dynamic ICF expansion will incur some overhead from
a system perspective. Each logical CP runs as an independent server of coupling
facility requests to the coupling facility using dynamic CF dispatching. Since the
resources used by each shared general purpose CP in this configuration subtract
from what could otherwise be used to run customer workloads, the number of
shared logical CPs defined to a coupling facility LP should be minimized.
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PR/SM Planning Guide