IBM eServer zSeries 990 Technical Guide

Chapter 2. System structure and design 27

򐂰 The IBM 2084 model D32 has four books (D) with 12 PUs in each book for a total of 48

PUs, of which 32 can be characterized by the customer. The remaining PUs are eight

system assist processors (SAPs) and eight spares, two of each in each book.

The last two digits of the model number reflect the maximum number of PUs that can be

characterized for installation use. The PUs can be characterized as CPs, IFLs, ICFs, zAAPs

or additional SAPs. The characters A, B, C, and D in the model number reflect the number of

books installed.

Whether one, two, three, or four books are present, to the user, all books together appear as

one Symmetric Multi Processor (SMP) with a certain number CPs, IFL, ICFs, and zAAPs a

certain amount of memory, and bandwidth to drive the I/O channels and devices. The

packaging is designed to scale to a 32-PU Symmetric Multi-Processor (SMP) server in four

books.

2.1.3 Memory

Maximum physical memory sizes are directly related to the number of books in the system.

Each book may contain a maximum of 64 GB of physical memory. The amount of memory on

each of the two memory cards in a book must be the same. The memory sizes in each book

do not have to be similar; different books may contain different amounts of memory. The

minimum orderable amount of memory is 16 GB, system-wide.

򐂰 A one-book system (IBM 2084-A08) may contain 16 GB, 32 GB, or 64 GB of physical

memory. Memory is orderable in 8 GB increments for customer use.

򐂰 A two-book system (IBM 2084-B16) may contain up to a maximum of 128 GB of physical

memory. For all memory card distribution variations in newly built two-book systems, refer

to Table 2-1 on page 28. Memory is orderable in 8 GB increments for customer use.

򐂰 A three-book system (IBM 2084-C24) may contain up to a maximum of 192 GB of physical

memory. For some memory card distribution variation in a newly built three-book system,

refer to Table 2-1 on page 28. Memory is orderable in 8 GB increments for customer use.

򐂰 A four-book system (IBM 2084-D32) may contain up to a maximum of 256 GB of physical

memory. For some memory card distribution variation in a newly built four-book system,

refer to Table 2-1 on page 28. Memory is orderable in 8 GB increments for customer use.

The system physical memory is the sum of all book memories. Not all books need to contain

the same amount of memory, and not all installed memory is necessarily configured for use.

Memory sizes

The minimum orderable amount of usable memory for all models is 16 GB. Memory upgrades

are available in 8 GB increments:

򐂰 IBM 2084 Model A08, from 16 to 64 GB

򐂰 IBM 2084 Model B16, from 16 to 128 GB

򐂰 IBM 2084 Model C24, from 16 to 192 GB

򐂰 IBM 2084 Model D32, from 16 to 256 GB

Physically, the memory cards are organized as follows:

򐂰 Each book always contains two memory cards. A memory card can come in three sizes:

–8 GB

– 16 GB

– 32 GB

򐂰 Within a given book, the card sizes must be equal, but all books do not necessarily need to

have the same amount of physical memory installed.