IBM System Storage Subsystem DS5020 - Manual (Page 102)

One DS5020 and three or more EXP520 storage expansion
enclosures
To connect three or more storage expansion enclosures to a DS5020 storage
subsystem, alternately connect a storage expansion enclosure to one of the drive
ports of the dual-ported drive channel then connect to the other port until all of the
storage expansion enclosures are attached. Figure 48 shows the cabling scheme
for one DS5020 storage subsystem and three EXP520 storage expansion
enclosures behind both ports of a dual-ported drive channel.
Perform the following steps to create the cabling scheme shown in Figure 48:
1. Connect port 1A on the left ESM in EXP520 one to port 1B on the left ESM in
EXP520 three.
2. Connect port 1A on the right ESM in EXP520 three to port 1B on the right ESM
in EXP520 one.
3. Connect port 1B on the left ESM in EXP520 one to port 2 of drive channel 1 on
the DS5020.
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
EXP520 one
EXP520 two
EXP520 three
Figure 48. One DS5020 and three EXP520 storage expansion enclosures behind a pair of
DS5020 drive ports
72 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide