I/O Connectivity

The Fibre Connection (FICON) channel on System z began shipping in volume in August of 1999 and was designed to be a replacement of Enterprise Systems Connection (ESCON) channels.   Over time the link data rate of the FICON channel has increased from 1 gigabits per second (Gbps), then 1 and 2 Gbp autonegotiated, followed by 1, 2, or 4 Gbps autonegotiated.  Today, the FICON channel supports a link data rate of 2, 4, or 8 Gbps autonegotiated.  The ESCON channel link data rate has remained constant, at 17 megabytes per second (MBps).

At introduction the FICON features supported the FICON protocol and access to Extended Count Key Data (ECKD) peripheral devices as well as FICON Channel-to-Channel (CTC).  The operating systems supported today are z/OS, z/VM, z/VSE, z/TPF, and Linux on System z environments.

In February of 2003 support for the Fibre Channel Protocol (FCP) was added which supports access to Small Computer System Interface (SCSI) peripheral devices.  The operating systems supported today are z/VM, z/VSE, and Linux on System z environments.

In October of 2008 High Performance FICON for System z (zHPF) became available. zHPF is a performance and reliability, availability, serviceability (RAS) enhancement of the z/Architecture and the FICON channel architecture implemented in zEnterprise EC12 (zEC12), zEnterprise BC12 (zBC12), zEnterprise 196 (z196), zEnteprise 114 (z114), and System z10 servers. Exploitation of zHPF by the FICON channel, the operating system, and the control unit is designed to help reduce the FICON channel overhead. This is achieved with protocol simplification and reduced number of information units (IUs) processed, resulting in more efficient use of the channel. The FICON Express8S, FICON Express8, FICON Express4, and FICON Express2 features support the FICON architecture, FICON channel-to-channel (CTC), and the zHPF architecture simultaneously. zHPF channel programs can be exploited by OLTP I/O workloads that transfer small (4K) blocks of fixed-sized data such as DB2, VSAM, PDSE, and zFS. For more information see Performance and What’s New.

FICON channels support fiber optic cabling – 50 and 62.5 micron fiber optic cabling for multimode fiber environments and 9 micron fiber optic cabling for single mode fiber environments.  For more information on FICON channels supporting FICON, CTC, zHPF, and FCP refer to the IBM System z Connectivity Handbook (SG24-5444) which can be found at: http://www.redbooks.ibm.com/

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