IBM Z9, Planning Manual

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1. If you do not specify a central storage origin, the reserved central storage is
available for the LP when there is sufficient physical storage available to meet
the reserved central storage request.
Storage can be reassigned between LPs that have noncontiguous address
ranges. Reconfiguration is not limited to growing into an adjacent LP. LPs are
eligible to use noncontiguous central storage if they have unique (not
overlapping) storage range definitions. Specifying an origin is not required
when defining a reserved storage amount for an LP, and by not specifying an
origin, the LP is reserved an addressable storage range for its entire storage
configuration (initial plus reserved amount). Not specifying an origin ensures
no overlap. The reserved central storage is available for LPs that do not
specify an origin when there is sufficient physical storage to meet the
reserved central storage request.
2. If you specify a central storage origin, the entire reserved central storage
amount is only available for the LP when:
– No other LP has this central storage address range, to which the reserved
central storage is mapped, online.
– There is sufficient physical storage available to meet the reserved central
storage request.
v If no origin is specified for an LP, the system assigns the storage to the LP using
a top-down first-fit algorithm. Storage that is part of reserved central storage for
another activated LP is not available for any LPs that do not specify a central
storage origin.
Expanded Storage
Optional expanded storage is defined to LPs before LP activation. When an LP is
activated, storage resources are allocated in contiguous blocks. These allocations
can be dynamically reconfigured. Sharing of allocated expanded storage among
multiple LPs is not allowed.
Expanded storage granularity is fixed at 64 MB. Expanded storage granularity
applies across the expanded storage input fields (Initial, Initial storage origin, and
Reserved fields).
When migrating to these models, you must convert any existing expanded storage
amounts that are not in multiples of the storage granularity supported.
For example, an LP with an initial expanded storage size of 10208 MB on a
previous model with 16 GB of storage installed would require conversion of the
initial expanded storage size to a multiple of 64 MB (32 MB granularity was valid on
this prior model configuration)
Use the Customize/Delete Activation Profiles task available from the CPC
Operational Customization Tasks list to open a reset or image profile to define the
expanded storage for an LP. The Initial, Initial storage origin, and Reserved fields
are located on the Storage page for the LP. See Figure 3-25 on page 3-73.
Check your expanded storage definitions and consult your system programmer to
ensure that they meet your processing needs.
Initial Expanded Storage
v The initial amount of expanded storage represents the amount of storage
allocated to an LP when it is activated. Expanded storage cannot be defined for
coupling facility mode LPs.
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PR/SM Planning Guide