Reserved Storage - IBM z13s Technical Manual

Linux only mode
In Linux only mode, storage addressing can be 31 bit or 64 bit, depending on the operating
system architecture and the operating system configuration, in the same way as in ESA/390
mode.
Only Linux and z/VM operating systems can run in Linux only mode. Linux on z Systems
64-bit distributions (SUSE Linux Enterprise Server 10 and later, and Red Hat RHEL 5 and
later) use 64-bit addressing and operate in z/Architecture mode. z/VM also uses 64-bit
addressing and operates in z/Architecture mode.
z/VM mode
In z/VM mode, certain types of processor units can be defined within one LPAR. This
increases flexibility and simplifies systems management by allowing z/VM to run the following
tasks in the same z/VM LPAR:
Manage guests to operate Linux on z Systems on IFLs
Operate z/VSE and z/OS on CPs
Offload z/OS system software processor usage, such as DB2 workloads on zIIPs
Provide an economical Java execution environment under z/OS on zIIPs
zACI mode
In zACI mode, storage addressing is 64 bit for an IBM zAware image running IBM z Advanced
Workload Analysis Reporter firmware. This configuration allows for an addressing range up to
16 EB. However, the current z13s definition limit for LPARs is 4 TB of storage.
Currently, the IBM zAware Version 2 feature, which is available on z13 and z13s servers, runs
in a zACI LPAR.
Important: The IBM zAware LPAR mode has been replaced for z13s and z13 servers at
Driver Level 27 with zACI. Existing IBM zAware LPARs will be automatically converted
during Enhanced Driver Maintenance from Driver 22 to Driver 27. No reconfiguration of
IBM zAware is required.
For more information, see Appendix B, "IBM z Systems Advanced Workload Analysis
Reporter (IBM zAware)" on page 453.

3.7.3 Reserved storage

Reserved storage can be optionally defined to an LPAR, allowing a nondisruptive image
memory upgrade for this partition. Reserved storage can be defined to both central and
expanded storage, and to any image mode except coupling facility mode.
An LPAR must define an amount of main storage and, optionally (if not a coupling facility
image), an amount of expanded storage. Both main storage and expanded storage can have
two storage sizes defined:
The initial value is the storage size that is allocated to the partition when it is activated.
The reserved value is an additional storage capacity beyond its initial storage size that an
LPAR can acquire dynamically. The reserved storage sizes that are defined to an LPAR do
not have to be available when the partition is activated. They are predefined storage sizes
to allow a storage increase, from an LPAR point of view.
Chapter 3. Central processor complex system design
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