IBM z/OS - Manual (Page 34)

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• Dynamic ICF Expansion: Dynamic ICF expansion pro-
vides value by providing extra CF capacity when there
are unexpected peaks in the workload or in case of loss
of CF capacity in the cluster.
– ICF Expansion into shared CPs. A CF partition running
with dedicated ICFs needing processing capacity
beyond what is available with the dedicated CP ICFs,
can “grow” into the shared pool of application CPs
being used to execute S/390 applications on the same
server.
– ICF Expansion into shared ICFs. A CF partition run-
ning with dedicated ICFs can “grow” into the shared
pool of ICFs in case the dedicated ICF capacity is not
suffi cient. The resulting partition, an “L-shaped” LPAR,
will be composed of both shared ICF and dedicated
ICF processors, enabling more effi cient utilization of
ICF resources across the various CF LPARs.
System-Managed CF Structure Duplexing
System-Managed Coupling Facility (CF) Structure Duplex-
ing provides a general purpose, hardware-assisted, easy-
to-exploit mechanism for duplexing CF structure data. This
provides a robust recovery mechanism for failures such as
loss of a single structure or CF or loss of connectivity to a
single CF, through rapid failover to the backup instance of
the duplexed structure pair.
Benefi ts of System-Managed CF Structure Duplexing
include:
• Availability
Faster recovery of structures by having the data already
there in the second CF, dramatically reducing the time
and processing required for structure rebuilds. System-
Managed Duplexing also provides basic recovery for
many structures that have no simple means to recover
data for failed structures, failed CFs, and losses of CF
connectivity.
• Manageability and Usability
A consistent procedure for duplexing does not “set
up” structures and manage structures across multiple
exploiters.
• Reliability
A common framework provides less effort on behalf
of the exploiters, resulting in more reliable subsystem
code.
• Cost Benefi ts
Facilitates the use of non-standalone CFs (e.g. ICFs) for
data sharing environments in addition to resource shar-
ing environments.
• Flexibility
The diagram below represents creation of a duplexed
copy of the structure within a System-Managed CF
Duplexing Confi guration.
Note: An example of two systems in a Parallel Sysplex with CF
Duplexing
A robust failure recovery capability
ICF z/OS z/OS ICF
z800/z900/z990/G5/G6 z800/z900/z990/G5/G6