IBM z/OS Server User Manual


 
34
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 struct
ures 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/OSz/OS ICF
z800/z900/z990/G5/G6
z800/z900/z990/G5/G6