IBM System Storage Subsystem DS5020 - Manual (Page 103)

4. Connect port 1 of drive channel 2 on the DS5020 to port 1B on the right ESM in
EXP520 three.
5. Connect port 1B on the left ESM in EXP520 two to port 1 of drive channel 1 on
the DS5020.
6. Connect port 1B on the right ESM in EXP520 two to port 2 of drive channel 2
on the DS5020.
Figure 49 on page 74 shows the cabling scheme for one DS5020 storage
subsystem and four EXP520 storage expansion enclosures behind both ports of a
dual-ported drive channel.
Chapter 3. Cabling the storage subsystem 73