IBM 990 - Manual (Page 17)

Chapter 1. zSeries 990 overview 5
Model upgrade paths
With the exception of the z900 Model 100, any z900 model may be upgraded to a z990
model. With the advancement of Linux for S/390 and Linux on zSeries, customers may
choose to 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.
Model downgrades
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.
Concurrent Processor Unit (PU) conversions
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, as shown in Figure 1-3.
Figure 1-3 System overview
1.3.1 Processor
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
Processor
4 flexible Models (A08, B16, C24 & D32)
64-bit Architecture
32 characterizable PUs, CMOS9G-SOI Technology
SuperScalar
Capacity Upgrade on Demand including Memory and I/O
Hybrid Cooling (Air/Liquid)
Up to 30 Logical Partitions
Optional ETR feature
Memory
64 GB per Model, max system memory 256 GB
Card sizes 8, 16, 32 GB (2 cards per Book)
Bi-directional redundant Ring Structure
I/O
64-bit Architecture (42/48-bit I/O addressing in hardware)
Up to 48 x 2 GB/s Self-Timed Interconnects (STIs)
I/O cage with enhanced power
Up to 4 Logical Channel Subsystems (LCSS)
Up to 120 FICON Express
™
Channels
FCP SCSI over Fibre Channel
Up to 48 OSA-Express network connectors
Crypto
SSL
PCIXCC
No CHPID number required
Up to 16 HiperSockets
Parallel Sysplex technology
ICB-4 (2 GB/s), ICB-3, ICB-2, ISC-3, IC
CF Duplexing
HMC
Alternate Service Element
Z frame
MDA MDA
MDA MDA
Cargo
IBF
IBF
MDA
A frame
MRU MRU
MDA MDA MDA MDA
MDA
IBF
B PD
Cargo
Dual SEs