Specifications

Controller images and interconnections
An ESS supports up to 16 controller images.
All controller images are accessible over any installed ESCON physical path. Each
controller image can have from 1 - 256 devices. The ranges of supported device
addresses may be noncontiguous. Devices that are not mapped to a logical device
respond and show address exceptions.
Note: When a primary controller connects to a secondary controller, the primary
connection converts to a channel. You cannot use it for host connectivity.
You can convert all 32 host attachments to channels. You should not use
more than 31 channels.
The controller images can handle the following ESCON interconnections:
v 1 - 256 devices (bases and aliases) per controller image
v 1 - 4096 devices (bases and aliases) with 16 controller images
v 1 - 128 logical paths per controller image
v 1 - 64 logical paths per ESCON Port (shared by all controller images)
v 2048 logical paths in the ESS
Support for 9032 Model 5 ESCON director FICON bridge feature
The ESS provides fibre-channel connectivity to S/390 and zSeries host systems
with the IBM 9032 Model 5 ESCON director. The 9032 FICON bridge provides
connection and switching among FICON channels and ESCON controllers.
Host adapters, cables, distances and specifications
Each ESCON host adapter connects to both clusters. An ESS emulates 0, 8, or 16
of the 3990 logical controllers. Half the logical controllers are in cluster 1 and half in
cluster 2. Because the ESCON adapter connects to both clusters, each adapter can
address 16 logical controllers.
Each ESCON host adapter provides two host connections. Order two ESCON
cables for each adapter for S/390 and zSeries hosts.
The standard distances for ESCON cables are 2 km (1.2 mi) with a 50-µm
multimode fibre and 3 km (1.9 mi) with 62.5-µm multimode fibre. You can extend
the distance of the cable to 103 km (64 mi) for the Peer-to-Peer Remote Copy
feature. You can also extend the distance of the cable to 103 km (64 mi) from
controller-to-controller.
Note: For optimum performance, use a cable shorter than 103 km (64 mi).
There is an ESCON channel on the S/390 and zSeries host systems. The S/390 or
zSeries host system attaches to one port of an ESCON host adapter in the ESS.
Each ESS adapter card has two ports.
See the IBM Enterprise Storage Server Introduction and Planning Guide for a list of
the ESCON host adapter features codes. The publication also contains the number
of ESCON host adapters, cable group number, number of cables, and connector
IDs to order for the cables.
70 ESS Host Systems Attachment Guide