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IBM phasing out ESCON channels on mainframes

IBM phases out ESCON channels on mainframes, which will eventually force shops to buy ESCON to FICON converters to support legacy devices.

SEATTLE -- IBM is phasing out ESCON channels on its mainframe hardware.

ESCON, or Enterprise Systems Connection, is a fiber-optic connection for mainframes and peripheral devices, introduced in the early 1990s to replace copper bus and tag connectors. FICON (Fiber Connectivity) is ESCON's faster, more efficient replacement.

IBM let users know ESCON's days were numbered in April 2009, burying a short statement of direction in a product newsletter. This week at the SHARE mainframe user group conference here, IBM got more explicit.

The current z10 mainframe will be the last iteration of Big Iron to support more than 240 ESCON channels (previously it had supported more than 1,000) and mainframe users should prepare for a phased transition from ESCON to FICON said Patty Driever, a senior engineer at IBM.

Moving from ESCON to FICON
Currently, there is no declared timeline for ending ESCON support altogether. "There are no plans yet to go from 240 ESCON channels to zero," Driever said.

The move from ESCON to FICON isn't new. Big Blue has recommended that all mainframes use FICON coming out of the host for over a decade. FICON features faster I/O rates, and longer distance capabilities that allow for greater network flexibility. FICON also supports full-duplex data transfers, which enables simultaneous reading and writing of data over a single link, and multiplexing, which enables small data transfers to be transmitted with larger ones, rather than having to wait until the larger transaction is finished.

But a lot of mainframe shops still rely on ESCON, and even bus and tag channel interfaces. "I can't do a wholesale switch to FICON," said one mainframe operator at the session. "I've got old devices that I have to support."

Another attendee concurred. "I've been trying to get rid of ESCON for years, but I've still got devices with bus-and-tag channels," he said after the presentation. "It's only a few devices -- printers and tape drives -- but I'm going to be stuck with them."

Mainframe shops supporting ESCON and bus and tag devices will need to install a FICON converter. Big Blue had its partner Optica Technologies Inc. on hand to tout its Prizm FICON to ESCON Converter. Prizm accepts a native FICON channel from the mainframe and converts the protocol to multiple outbound ESCON channels.

According to a 2008 survey by zJournal, more than 80% of mainframe users support ESCON devices in their data centers.

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