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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 wait at least 70 seconds after you turn off the power before you turn
on the power again.
Power-off overview
Review the following information before you continue with the power-off
procedure:
Turn off the power to each device according to the following shutdown sequence:
1. Turn off power to the host before the storage subsystem. If the host must stay
powered-on to support a 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 enclosures. Turn off both power-supply switches on the rear of the
storage subsystem.
3. If there are enclosures with dc power supplies in your storage subsystem, turn
off the -48V disconnect devices after turning off the power-supply switches.
96 IBM System Storage DS3500 and EXP3500 Storage Subsystem: Installation, User's, and Maintenance Guide