6947ch03.fm Draft Document for Review April 7, 2004 6:15 pm
74 IBM eServer zSeries 990 Technical Guide
3.1 Overview
The z990 I/O system design provides great flexibility, high availability and performance,
allowing:

High bandwidth

The z990 I/O system can handle up to 96 GB/sec, which is four times the z900 server’s
bandwidth. Individual channels can have up to 2 Gb/sec and individual Coupling Facility links
up to 2 GB/sec data rates.

Wide connectivity

A z990 server can be connected to an extensive range of interfaces, using protocols such as
Fibre Channel Protocol (FCP) for Small Computer System Interface (SCSI), Gigabit Ethernet
(GbE), 1000BASE-T Ethernet, 100BASE-T Ethernet, 10BASE-T Ethernet, Token Ring along
with FICON Express, ESCON and coupling links channels.

Cryptographic functions

The z990 I/O system also supports optional cryptographic cards to complement the standard
CP Assist for Cryptographic Function (CPACF) that is implemented in every PU, enhancing
the performance of cryptographic processing.

Concurrent I/O upgrades

It is possible to concurrently add I/O cards to a z990 server provided there are unused slot
positions in an I/O cage. Additional I/O cages can be previously installed on an initial
configuration, via CUoD, to provide greater capacity for concurrent upgrades. This capability
may help eliminate an outage to upgrade the I/O configuration. See more information about
concurrent upgrades on Chapter8, “Capacity upgrades” on page 185.

Dynamic I/O configuration

Dynamic I/O configuration enhances system availability by supporting the dynamic addition,
removal, or modification of channel paths, control units, I/O devices, and I/O configuration
definitions to both hardware and software (if it has this support) without requiring a planned
outage.

ESCON port sparing and upgrading

The ESCON 16-port I/O card includes one unused port dedicated for sparing in the event of a
port failure on that card. Other unused ports are available for growth of ESCON channels
without requiring new hardware, enabling concurrent upgrades via Licensed Internal Code
(LIC).
The following I/O feature ports are supported in the zSeries 990 server:
򐂰Up to 1024 ESCON (up to 720 ESCON on model A08)
򐂰Up to 120 Fibre Connection (FICON) Express (up to 96 FICON on model A08)
򐂰Up to 48 Open Systems Adapter (OSA) Express
򐂰Up to 16 Integrated Cluster Bus-4 (ICB-4) (up to 12 ICB-4 on model A08)
򐂰Up to 16 Integrated Cluster Bus-3 (ICB-3)
򐂰Up to 8 Integrated Cluster Bus-2 (ICB-2)
򐂰Up to 48 Inter-System Channel-3 (ISC-3) in peer mode (up to 32 ISC-3 in compatibility
mode)
򐂰Up to 2 External Time Reference (ETR)
Note: The maximum number of Coupling Links combined (IC, ICB-2, ICB-3, ICB-4, and
active ISC-3 links) cannot exceed 64 per z990 server.