IBM System Storage Subsystem DS5020 - Manual (Page 88)

Important: The DS5020 supports the connection of a maximum of six storage
expansion enclosures per redundant drive channel pair. The DS5020
supports one redundant drive channel pair.
If you are using fiber-optic cables, install SFP modules into the ports that will
receive the cables before installing the cables.
Figure 36 and shows the locations of controllers A and B, the single-ported Fibre
Channel host channels, Ethernet ports, and dual-ported Fibre Channel drive
channels at the back of the DS5020 storage subsystem.
Note: Your DS5020 hardware might differ slightly from the following illustration.
Notes:
1. EXP810 and EXP520 storage expansion enclosures can be intermixed behind a
DS5020 drive channel.
2. To cable EXP810 storage expansion enclosures with a DS5020, you must
purchase the Attach EXP810 to DS5020 Activation feature option.
Controller B
Controller A
Host
port 4 Host
port 3 Host
port 2 Host
port 1
Host
port 1 Host
port 2 Host
port 3 Host
port 4 Drive Channel 1 -
Port 2 on Controller A Drive Channel 1 -
Port 1 on Controller A
Drive Channel 2 -
Port 2 on Controller B
Drive Channel 2 -
Port 1 on Controller B
Figure 36. DS5020 storage subsystem ports and controllers
58 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide