IBM 990 User Manual
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zSeries 990 Technical Guide
ICB-3 (Integrated Cluster Bus 3)
The Integrated Cluster Bus-3 (ICB-3) link is a member of the family of Coupling Link options
available on z990. Like the ISC-3 link, it is used by coupled systems to pass information back
and forth over high speed links in a Parallel Sysplex environment. ICB-3 or ISC-3 links are
used to connect z900, z800, or z890 servers (2064, 2066, or 2086) to z990 servers.
An STI-3 card resides in the I/O cage and provides two output ports to support the ICB-3
connections. The STI-3 card converts the 2 GBps input into two 1 GBps ICBs. The ICB-3 is
defined in peer mode and the link speed is 1 GBps.
One feature is required for each end of the link. Ports are ordered in increments of one.
ICB-4 (Integrated Cluster Bus 4)
The Integrated Cluster Bus-4 (ICB-4) link is a member of the family of Coupling Link options
available on z990. ICB-4 is a “native” connection used between z990 and or z890 processors.
An ICB-4 connection consists of one link that attaches directly to an STI port in the system,
does not require connectivity to a card in the I/O cage, and operates at 2 GBps. The ICB-4
works in peer mode and the link speed is 2 GBps.
One feature is required for each end of the link. Ports are ordered in increments of one.
Internal Coupling (IC)
The Internal Coupling-3 (IC) channel emulates the Coupling Facility functions in LIC between
images within a single system. No hardware is required; however, a minimum of two CHPID
numbers must be defined in the IOCDS for each connection.
System-Managed CF Structure Duplexing
System-Managed Coupling Facility (CF) Structure Duplexing provides a general purpose,
hardware-assisted, easy-to-exploit mechanism for duplexing CF structure data. This provides
a robust recovery mechanism for failures (such as loss of a single structure or CF or loss of
connectivity to a single CF) through rapid failover to the other structure instance of the duplex
pair.
The following three structure types can be duplexed using this architecture:
Cache structures
List structures
Locking structures
Support for these extensions is included in Coupling Facility Control Code (CFCC) Levels 11
12, and 13 and in z/OS V1.2, V1.3, V1.4, and V1.5 and later.
For those CF structures that support the use of System-Managed CF Structure Duplexing,
customers have the ability to dynamically enable or disable, selectively by structure, the use
of System-Managed CF Structure Duplexing.
Customers interested in deploying System-Managed CF Structure Duplexing in their test,
development, or production Parallel Sysplex will need to read the technical paper
System-Managed CF Structure Duplexing, GM13-0100 and analyze their Parallel Sysplex
environment to understand the performance and other considerations of using this function.
System-Managed CF Structure Duplexing, GM13-0100 is available at these Web sites: