IBM eServer zSeries 900 Technical Guide

52 IBM eServer zSeries 900 Technical Guide

Hiperspaces on z/Architecture mode

Hiperspace services have been re-implemented to use central storage rather than expanded

storage. All of the Hiperspace APIs, as well as the Move Page (MVPG) instruction, continue

to operate in a compatible manner. There is no need to change products that use

Hiperspaces.

Hardware System Area

The Hardware System Area (HSA) is a non-addressable storage area that contains the CPC

Licensed Internal Code and configuration-dependent control blocks. The HSA size varies

according to:

򐂰 Power-On-Reset mode of the CPC.

򐂰 Number of installed processors.

򐂰 Size and complexity of the system I/O configuration.

򐂰 The expansion percentage used for dynamic I/O configuration.

For planning purposes, you can assume the following HSA maximum sizes:

– Basic mode: 144 MB.

– LPAR mode and memory <= 32 GB: 288 MB.

– LPAR mode and memory > 32 GB: 384 MB.

The z900’s HSA can have up to 63K subchannels per logical partition and up to 512K

subchannels in total.

2.5.2 Storage operations

In the z900 servers, memory can be assigned as a combination of central storage and

expanded storage, supporting up to 15 logical partitions in LPAR mode.

Before one can activate a logical partition, central storage (and optional expanded storage)

must be defined to the logical partition. In LPAR mode, all installed storage can be configured

as central storage. Each individual logical partition can be defined to a maximum of 2 GB (in

ESA/390 architecture mode) or the current maximum 64 GB (in z/Architecture mode) of

central storage.

In LPAR mode, central storage can be dynamically assigned to expanded storage and back to

central storage as needed, without a Power-On-Reset (POR). See “LPAR single storage pool”

on page 51.

Memory

cannot be shared between system images. When a logical partition is activated, the

storage resources are allocated in contiguous blocks. You can dynamically reallocate storage

resources for z/Architecture and ESA/390 Architecture mode logical partitions running

operating systems that support Dynamic Storage Reconfiguration (DSR). See “LPAR

Dynamic Storage Reconfiguration” on page 56.

Operating systems running under z/VM can exploit the z/VM capability of implementing virtual

memory to guest virtual machines. The z/VM dedicated

real storage can be “shared”

between guest operating systems’ memories.

Figure 2-16 shows the z900 modes and memory diagram, which summarizes all image

modes, with their processor types and the Central Storage (CS) and Expanded Storage (ES)

definitions allowed for each mode.

Chapter 2. zSeries 900 system structure 53

Figure 2-16 Modes and memory diagram

Table 2-8 shows the z900 storage

allocation and usage possibilities, which depend upon the

image and architecture modes.

Table 2-8 Storage definition and usage possibilities

Remember that either a z/Architecture mode or an ESA/390 architecture mode operating

system can run in an ESA/390 mode on a z900. Any ESA/390 image, in Basic mode or in

LPAR mode, can be configured with more than 2 GB of central storage

and can have

expanded storage. These options allow you to configure more storage resources than the

operating system is capable of addressing.

ESA/390 mode

In ESA/390 mode, storage addressing can be 31 or 64 bits, depending on the operating

system architecture

and the operating system configuration.

Image mode Architecture mode

(addressability)

Maximum central storage Expanded storage

Architecture z900

definition

z900

definable

Operating

system usage

ESA/390 z/Architecture (64-bit) 16 EB 64 GB yes only by z/VM

ESA/390 (31-bit) 2 GB 64 GB yes yes

ESA/390 TPF ESA/390 (31-bit) 2 GB 64 GB yes yes

Coupling Facility CFCC (64-bit) 16 EB 64 GB no no

Linux Only z/Architecture (64-bit) 16 EB 64 GB yes

only by z/VM

ESA/390 (31-bit) 2 GB 64 GB yes yes

z900 CPC

Modes

ESA/390

Mode

Logically

Partitioned

Mode

ESA/390 Mode

ESA/390 TPF Mode

Coupling Facility Mode

Linux Only Mode

CPs

only

CPs

only

ICFs

and/or

CPs

IFLs

or

CPs

ESA/390 TPF

Mode

Image

Modes

Definable Central Storage (CS)

and Expanded Storage (ES)

CS < = 64 GB

ES = Yes

CS < = 64 GB

ES = Yes

CS < = 64 GB

ES = No

CS < = 64 GB

ES = Yes