IBM System Storage Subsystem DS5020 - Manual (Page 93)

One DS5020 and four storage expansion enclosures
If you are cabling one DS5020 storage subsystem and four storage expansion
enclosures, Figure 41 shows the correct cabling topology.
1A 1B
DS5020
Port 2, drive channel 1
1A 1B
1A 1B
1A 1B
Port 1, drive channel 1
Port 1, drive channel 2
Port 2, drive channel 2
1A 1B
1A 1B
1A 1B
1B 1A
Figure 41. Cabling for one DS5020 and four storage expansion enclosures
Chapter 3. Cabling the storage subsystem 63