IBM System Storage Subsystem DS5020 - Manual (Page 140)

Statement 5:
CAUTION:
The power control button on the device and the power switch on the power
supply do not turn off the electrical current supplied to the device. The device
also might have more than one power cord. To remove all electrical current
from the device, ensure that all power cords are disconnected from the power
source.
1
2
CAUTION:
This unit has more than one power source. To remove all power from the unit,
all MAINS must be disconnected.
Attention: Turning off and turning on power without waiting for the storage
subsystem disk drives to spin down can damage the drives and might cause data
loss. Always let at least 70 seconds elapse from when you turn off the power until
you turn on the power again.
Power-off overview
Review the following information before you continue with the power-off
procedure below.
Turn off the power to each device based on the following shutdown sequence:
1. Turn off power to the host before the storage subsystem. If the host must
stay powered on to support an existing network, see the operating system
documentation for information about disconnecting the storage subsystem
logical drives from the host before the storage subsystem is powered off.
2. Turn off power to the storage subsystem before you turn off power to the
storage expansion enclosures. Turn off both power supply switches on the
back of the storage subsystem.
3. Turn off power to other supporting devices (for example, management
stations, Fibre Channel switches, or Ethernet switches).
Note: You do not need to perform this step if you are servicing only the
storage subsystem.
110 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide