IBM 88743BU - System x3950 E User Manual page 164

Figure 3-32 EXP3000: rear view cabling
4. Turn on the EXP3000 expansion units before or at the same time as you turn
on the device that contains the RAID controller.
Figure 3-33 on page 147 shows the components of the ESM.
146
Planning, Installing, and Managing the IBM System x3950 M2