Logical Partition Storage Granularity - IBM z13s Technical Manual

Without the reserved storage definition, an LPAR storage upgrade is a disruptive process that
requires the following actions:
1. Partition deactivation
2. An initial storage size definition change
3. Partition activation
The additional storage capacity for an LPAR upgrade can come from these sources:
Any unused available storage
Another partition that has released storage
A memory upgrade
A concurrent LPAR storage upgrade uses DSR. z/OS uses the reconfigurable storage unit
(RSU) definition to add or remove storage units in a nondisruptive way.
z/VM V6R2 and later releases support the dynamic addition of memory to a running LPAR by
using reserved storage. It also virtualizes this support to its guests. Removal of storage from
the guests or z/VM is disruptive.
SUSE Linux Enterprise Server 11 supports both concurrent add and remove.

3.7.4 Logical partition storage granularity

Granularity of main storage for an LPAR depends on the largest main storage amount that is
defined for either initial or reserved main storage, as shown in Table 3-7.
Table 3-7 Logical partition main storage granularity (z13s servers)
Logical partition:
Largest main storage amount
Main storage amount <= 256 GB
256 GB < main storage amount <= 512 GB
512 GB < main storage amount <= 1 TB
1 TB < main storage amount <= 2 TB
2 TB < main storage amount <= 4 TB
The granularity applies across all main storage that is defined, both initial and reserved. For
example, for an LPAR with an initial storage amount of 30 GB and a reserved storage amount
of 48 GB, the main storage granularity of both initial and reserved main storage is 512 MB.
Expanded storage granularity is fixed at 512 MB.
Removal of support for Expanded Storage (XSTORE): The IBM z13 and z13s servers
are the last z Systems servers to support Expanded Storage (XSTORE).
All statements regarding IBM plans, directions, and intent are subject to change or
withdrawal without notice. Any reliance on these statements of general direction is at the
relying party's sole risk and will not create liability or obligation for IBM.
LPAR storage granularity information is required for LPAR image setup and for z/OS RSU
definition. LPARs are limited to a maximum size of 10 TB of main storage (4 TB on z13s
servers). For z/VM V6R2, the limit is 256 GB, whereas for z/VM V6.3, the limit is 1 TB.
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IBM z13s Technical Guide
Logical partition:
Main storage granularity
512 MB
1 GB
2 GB
4 GB
8 GB