IBM Z9, Planning Manual

Page: 63 / 274

ESCON Example: Figure 2-1 shows a situation where 20 ESCON channel paths
routed through an ESCON Director (ESCD) each attempt to establish a logical path
to a 3990 Storage Control. The 3990 will allocate all 16 of its logical paths among
the 20 channel paths dynamically on a first-come-first-served basis. Clearly, some
of the ESCON channel paths will not operate in this configuration. Managing logical
paths can provide a way to alleviate this situation.
LP1 LP2 LP3 LP4 LP5
C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C C
N
C
3990
ESCD
Cluster 1 Cluster 2
Each of the 20 channels
attempts to establish
one logical path.
Figure 2-1. An ESCON Configuration that Can Benefit from Better Logical Path Management
Chapter 2. Planning Considerations
2-9