IBM 990 1.3 System functions and features

Chapter 1. IBM zSeries 990 overview 5

Draft Document for Review April 7, 2004 6:15 pm 6947ch01.fm

change the PU characterization of the server they are upgrading. In addition, customers who

are consolidating may not be increasing total capacity, and/or they may wish to take

advantage of the multiple Logical Channel Subsystems offered. z990-to-z990 model

upgrades and feature adds may be completed concurrently.

There are no model downgrades offered. Customers may purchase unassigned CPs or IFLs

for future use. This avoids the placement of RPQ orders and subsequent sequential MES

activity, and paying software charges for capacity that is not in use.

z990 servers support concurrent conversion between different PU types, providing flexibility

to meet changing business environments. Assigned CPs, unassigned CPs, assigned IFLs,

unassigned IFLs, and ICFs may be converted to assigned CPs, assigned IFLs or ICFs, or to

unassigned CPs or unassigned IFLs.

1.3 System functions and features

The 990 system offers the following functions and features.

IBM introduced the Processor Resource/Systems Manager™ (PR/SM) feature in February

1988, supporting a maximum of four logical partitions. In June 1992, IBM introduced support

for a maximum of 10 logical partitions and announced the Multiple Image Facility (MIF, also

known as EMIF), which allowed sharing of ESCON channels across logical partitions—and

since that time has allowed sharing of more channels across logical partitions (such as

Coupling Links, FICON and OSA). In June 1997, IBM announced increased support - up to

15 logical partitions on Generation 3 and Generation 4 servers.

The evolution continues and IBM is announcing support for 30 logical partitions. This support

is exclusive to z990 and z890 models.

The z990 12-PU MCM is smaller and more capable than the z900’s 20-PU MCM. It has

16 chips, compared to 35 for the z900. The total number of transistors is over 3 billion,

compared with approximately 2.5 billion for the z900. With this amazing technology

integration comes improvements in chip-to-substrate and substrate-to-board connections.

The z990 module uses a connection technology, LAN Grid Arrays (L GA), pioneered by the

pSeries™ in the p690 and the i890. LGA technology enables the z990 substrate, with only

53% of the surface area of the z900 20 PU MCM substrate, to have 23% more I/Os from the

logic package.

Both the z900 and z990 have 101 layers in the glass ceramic substrate. The z990's substrate

is thinner, shortening the paths that signals must travel to reach their destination (another chip

or exiting the MCM). Inside the low dielectric glass ceramic substrate is 0.4 km of internal

wiring that interconnects the 16 chips that are mounted on the top layer of the MCM. The

internal wiring provides power and signal paths into and out of the MCM.

The MCM on the z990 offers flexibility in enabling spare PUs via the Licensed Internal Code

Configuration Control (LIC-CC) to be used for a number of different functions. These are:

򐂰A Central Processor (CP)