Avago Technologies LSI53C180 - Manual (Page 13)

General Description 1-3
1.1.1 Applications
•
Server clustering environments
•
Expanders creating distinct SCSI cable segments that are isolated
from each other
Figure 1.2 LSI53C180 Server Clustering
Figure 1.2 demonstrates how SCSI bus expanders are used to couple
bus segments together without any impact on the SCSI protocol or
software. Configurations that use the LSI53C180 SCSI Bus Expander in
the Ultra160 mode (LVD to LVD) allow the system designer to take
advantage of the inherent cable distance, device connectivity, data
reliability, and increased transfer rate benefits of LVD signaling with
Ultra160 SCSI peripherals.
In the Figure 1.2 example, two LSI53C180 expanders are used to
configure three segments. This configuration allows segment A to be
treated as a point-to-point segment. Segments B and C are treated as
load segments with at least 8 inches between every node.
Table 1.2
shows the various distance requirements for each SCSI bus mode.
Segment A Segment B
Segment C
Primary Server Secondary Server
Shared Disk Subsystem
SCSI Bus
Expander
SCSI Bus
Expander