IBM 990 Reference Manual page 44

Automatic Enablement of CBU for Geographically Dispersed
Parallel Sysplex
The intent of the GDPS (CBU) is to enable automatic man-
agement of the reserved PUs provided by the CBU feature
in the event of a processor failure and/or a site failure.
Upon detection of a site failure, GDPS will dynamically
add PUs to the confi guration in the takeover site to restore
processing power for mission-critical production work-
loads. GDPS-CBU management helps to minimize manual
customer intervention and the potential for errors, thereby
helping to reduce the outage time for critical workloads
from hours to minutes. Similarly, GDPS-CBU management
can also automate the process of dynamically returning
the reserved CPs when the temporary period has expired.
GDPS is discussed in a white paper available at ibm.com/
server/eserver/zseries/pso/library.html. GDPS is a service
offering of IBM Global Services. For IBM Installation Ser-
vices for GDPS, refer to the IBM Web site.
Message Time Ordering (Sysplex Timer Connectivity to Coupling
Facilities)
As processor and Coupling Facility link technologies have
improved over the years, the requirement for time synchro-
nization tolerance between systems in a Parallel Sysplex
environment has become ever more rigorous. In order
to ensure that any exchanges of timestamped informa-
tion between systems in a sysplex involving the Coupling
Facility observe the correct time ordering, time stamps are
now included in the message-transfer protocol between
the systems and the Coupling Facility. Therefore, when a
Coupling Facility is confi gured as an ICF on any z990 or
z900 Models 2C1 through 216, the Coupling Facility will
require connectivity to the same 9037 Sysplex Timer that
the systems in its Parallel Sysplex cluster are using for
time synchronization. If the ICF is on the same server as a
member of its Parallel Sysplex environment, no additional
connectivity is required, since the server already has
connectivity to the Sysplex Timer. However, when an ICF
is confi gured on any z990 or z900 Models 2C1 through
216 which do not host any systems in the same Parallel
Sysplex cluster, it is necessary to attach the server to the
9037 Sysplex Timer.
z900 Turbo or z890/z990 Model with ICF
and non-Parallel Sysplex LPARs
Non-Sysplex
LPARs
IBM ^ z900
or z890/z990
Sysplex
z/OS
LPARs
IC
CF02
CF02
ICF
ICF
12
11 1
10 2
9 3
8 4
7 5
6
44
CF01
ICF
z/OS
IBM ^ z900
or z890/z990
Sysplex
z/OS
LPARs
12
11 1
10 2
9 3
8 4
7 5
6