192 IBM eServer zSeries 900 Technical Guide
A compatible secondary volume must be available for each primary volume you want to
copy. The secondary volume must have the same geometry as the primary volume with an
equal or greater capacity.
GDPS/XRC software requirements
In addition to the GDPS/PPRC software prerequisites, XRC with ESS also requires the
following:
DFSMS/MVS 1.4.0 or above, with System Data Mover function
OS/390 V2 R6 or later
Figure 5-7 GDPS/XRC
5.4.3 GDPS and z900 features
GDPS consists of production images and controlling images. The production images execute
the mission critical workload. There must be sufficient processing resource capacity, such as
processor capacity, main storage, and channel paths available that can quickly be brought
on-line to restart an image's or site's critical workload (typically by terminating one or more
systems executing expendable [non-critical] work and acquiring their processing resource).
The Capacity Backup (CBU) feature, available on the z900, provides a significant cost
savings. The CBU feature has the ability to increment capacity temporarily, when capacity is
lost elsewhere in the enterprise. CBU adds Central Processors (CPs) to the available pool of
processors and is activated only in an emergency. GDPS-CBU management automates the
process of dynamically adding reserved Central Processors, thereby minimizing manual
customer intervention and the potential for errors. The outage time for critical workloads can
be reduced from hours to minutes.
The controlling image coordinates GDPS processing. By convention all GDPS functions are
initiated and coordinated by the controlling image.
Channel
Extenders
CE
CE
CE
CE
Site A
Application
Systems
Application
Systems
Site B
Secondary
volumes
and SDM
Control Data sets
Primary
volumes
SW SW
Recovery
Systems
SDM System
Data mover
CF01
1
2
3
4
5
6
7
8
9
10
11
12
Chapter 5. Sysplex functions 193
All GDPS images are running GDPS automation based upon Tivoli Netview for OS/390 and
System Automation for OS/390. Each image will monitor the base or Parallel Sysplex cluster,
Coupling Facilities, and storage subsystems; and maintain GDPS status. GDPS automation
can coexist with an enterprise's existing automation product.
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