Multi-Tech Systems 40-01459-D0-001 manual Escon Configuration, Overview

Chapter 4. ESCON CONFIGURATION

Figure 4-1. ESCON Attached Controllers

Overview

ESCON controllers, including the PCI ESCON Adapter (PBSA), can be connected to the mainframe in more than one fashion. As shown in Figure 4-1, Controller 1 is attached directly to one of the mainframe’s ESCON channels. Assuming the mainframe is running a single Logical Partition (LPAR), this is simplest option for connecting an ESCON controller to the mainframe. However, connecting an ESCON controller directly to a mainframe’s ESCON channel in this fashion imposes two restrictions:

1.Only a single controller can be attached to a mainframe’s channel.

2.The controller is only able to communicate with a single mainframe, the one it is physically attached to.

An ESCON director overcomes these restrictions by attaching multiple “downstream” controllers and by supporting multiple ESCON interfaces to multiple mainframes. In Figure 4-1, Controllers 2 – 4 are connected to the director which is then connected to two ESCON channels, one on each of two mainframes.

Some mainframes also support multiple, Logical Partitions (LPARs) running on a single system; logically making the system appear as multiple computers. The ESCON Multiple-Image Facility (EMIF) can be used in those environments to allow sharing of ESCON channel paths across partitions. In Figure 4-1, a single channel path defined between the mainframe and Controller 5 can be shared by both LPAR P1 and LPAR P2 using EMIF.

ESCON Configuration 15