IBM Z9, Planning Manual

Page: 120 / 274

Concurrent Memory Upgrade
The System z9 includes a function to dynamically increase the amount of
configured storage. Concurrent Memory Upgrade allows for a memory upgrade
without changing hardware or experiencing an outage, provided there is enough
spare memory already existing on the memory cards. An IML is not required to use
the previously unavailable storage. It is immediately available for allocation to
logical partitions as either central or expanded storage. The new storage can be
allocated to either newly activated logical partitions or to already active logical
partitions by using dynamic storage reconfiguration (see “Dynamic Storage
Reconfiguration” on page 3-12). In planning for a concurrent memory upgrade,
logical partition activation profiles should be defined with storage (central and/or
expanded) specifications that include a reserved as well as an initial storage
amount. Following the completion of the concurrent memory upgrade operation,
issue the z/OS command CF STOR(E=1),ONLINE or the z/OS command CF
ESTOR(E=1),ONLINE to bring the new memory online to already active LPs for
which a reserved central storage amount, or a reserved expanded storage amount
(respectively) was specified.
Capacity Backup Upgrade (CBU) Capability
This orderable feature, available on z9 EC Models, can be integrated with
Geographically Dispersed Parallel Sysplex
™
. This should reduce disaster recovery
times by automating the Capacity Backup Upgrade process at a remote site.
Operationally, the planning considerations and limitations for Capacity Backup
Upgrade, for mode purposes, are similar to those for Dynamic Capacity Upgrade on
Demand. Planning is simple because reserved logical CPs can be specified for
logical partitions on the backup system. The logical CPs can then be brought
online, quickly and nondisruptively.
Concurrent Undo CBU is provided to dynamically remove from the configuration
processors that had been added via Capacity Backup Upgrade. The server for
disaster recovery with Capacity Backup Upgrade activated can now be restored to
its base configuration without requiring a system outage.
When a disaster occurs, Capacity Backup Upgrade is intended to provide the extra
capacity without disruption. When the disaster is over and normalcy is restored,
Concurrent Undo CBU is intended to allow the system to be returned to its previous
configuration without disruption.
Annual testing of a Capacity Backup Upgrade system is highly recommended.
Invoking the Capacity Backup Upgrade configuration is nondisruptive and now
returns to the original configuration, after the test, without disruption as well.
When a typical Capacity Backup Upgrade occurs, usually logical processors are
configured online so that the system closely resembles the failing system. To
prepare for Concurrent Undo CBU, the most expedient method is to simply
configure offline all those logical processors that were configured online in support
of the failing system.
In order for Concurrent Undo CBU to proceed, the restored original configuration
must have a physical processor for each online dedicated logical processor.
Theoretically, the only additional requirement is that at least one nondedicated
physical processor remains that matches each type (general purpose, ICF, IFL, IFA
or zIIP) of online shared logical processors. However, it is highly recommended that
2-66
PR/SM Planning Guide