The z990 supports concurrent memory upgrade. This capa-
bility will allow a processor’s memory to be increased with-
out disrupting the processor operation. To take advantage
of this capability, a customer should not plan processor
storage on the 16 or 32 GB increments. A customer with a
Model A08, for example, with 24 GB of storage will be able
to concurrently upgrade to 32 GB but will not be able to get
to the next increment of 40 GB without a disruption.
Plan Ahead for PUs is done by ordering a “more book”
model. For example, if a customer needs 5 PUs initially,
but plans to grow to need 10 PUs, he should not order an
A08, but a Model B16 with only 5 PUs initially active.
The Plan Ahead process can easily identify the customer
conﬁ guration that is required to meet future needs. The
result of concurrent conditioning is a ﬂ exible IT infrastruc-
ture that can accommodate unpredictable growth in a low
risk, nondisruptive way. Depending on the required Con-
current Conditioning, there should be minimal cost associ-
ated with dormant z990 capacity. This creates an attractive
option for businesses to quickly respond to changing
environments, bringing new applications online or growing
existing applications without disrupting users.
z990 Server Capacity BackUp (CBU)
Capacity BackUp (CBU) is offered with the z990 servers
to provide reserved emergency backup CPU capacity for
situations where customers have lost capacity in another
part of their establishment and want to recover by adding
reserved capacity on a designated z990 server. A CBU
system normally operates with a “base” CP conﬁ guration
and with a preconﬁ gured number of additional Processor
Units (PUs) reserved for activation in case of an emergency.
The z990 technology is suited for providing capacity
backup. The reserved CBU processing units are on the
same technology building block, the MCM, as the regular
CPs. Therefore, a single server can support two diverse
conﬁ gurations with the same MCM. For CBU purposes, the
Models A08, B16, C24 & D32 can scale from a 1-way to a
32-way; with the purpose of providing capacity backup.
The “base” CBU conﬁ guration must have sufﬁ cient
memory and channels to accommodate the potential
needs of the larger CBU target machine. When capacity is
needed in an emergency, the primary operation performed
is activating the emergency CBU conﬁ guration with the
reserved PUs added into the conﬁ guration as CPs.
Customers who have an active Remote Support Facility
connection can perform a CBU upgrade automatically and
within a matter of minutes, right from their CBU machine’s
Hardware Management Console (HMC). For more informa-
tion on how a CBU upgrade can be activated automati-
cally, please refer to the z990 Capacity BackUp Users'
Guide found on IBM Resource Link.
The z990 supports concurrent CBU downgrade. This func-
tion enables a Capacity BackUp server to be returned to
its normal conﬁ guration without an outage (i.e. PowerOn
Reset).Automatic Enablement of CBU for Geographically Dispersed Parallel Sysplex (GDPS)
The intent of GDPS support for CBU is to enable auto-
matic management 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 processor failure or site
failure, GDPS will activate CBU to dynamically add PUs to