NEC S2900 User Manual page 86

(3) Turning off the AC power
a) To turn off the power, turn off the host system or the FC-AL switch, and then perform the
procedure shown in "(2) Notes on turning off the AC power".
b) Push the SHUTDOWN switch for at least five seconds to write any data remaining in the
cache memory onto the disk before turning off the AC power when:
you turn off the AC power for any long period
–
you replace any of the controllers, power supplies, or battery backup units in power-off
–
state.
See Item (2) "Notes on turning off AC power".
c) Turn off the array controller and then disk enclosures. Alternatively, turn off the array
controller and all the FC disk enclosures connected with the array controller at the same time.
The disk array unit has a redundant power configuration to prevent the entire unit from
shutting down due to a single failure. Therefore, when turning off the disk array unit, turn off
all the power switches (of the array controller and disk enclosures) at the rear of the unit.
Be aware that data may be lost if you turn off the disk enclosures before the array controller.
[Power-off procedure]
Turn off the power switches in the following order (1) to (3):
(3) Power switches of disk enclosures
(May be turned off at the same time the power switches of
array controller are turned off.)
(2) Power switches of array controller
69
(1) Host system