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the appropriate DS4000 Storage Subsystem Installation, User's, and
Maintenance Guide during any attended power-up procedure.
v A storage subsystem in an optimal state should recover automatically
from an unexpected shutdown and unattended simultaneous
restoration of power to system components. After power is restored,
contact IBM technical support if any of the following conditions occur:
– The storage subsystem logical drives and subsystems do not
display in the Storage Manager graphical user interface (GUI).
– The storage subsystem logical drives and subsystems do not come
online.
– The storage subsystem logical drives and subsystems seem to be
degraded.
4. Turn on the power to each device, based on the startup sequence.
5. (DS4700 Express dc models only) Turn on any attached disconnect devices.
6. Turn on both of the power supply switches on the DS4700 Express. The green
LEDs on the front and the back of the DS4700 Express should remain lit. If
other amber Fault LEDs light, see “Solving problems” on page 183.
Recovering from an overheated power supply and fan unit
Each storage subsystem contains two power supply and fan units. Each power
supply and fan unit contains a built-in temperature sensor designed to prevent it
from overheating. Under normal operating conditions, with an ambient air
temperature range of 10° C to 35° C (50° F to 95° F), the fans in the power supply
and fan units maintain a proper operating temperature inside the module.
If the internal temperature reaches 65° C (149° F), the power supply shuts down
automatically. If both power supplies shut down because of overheating, the module
has no power, and all indicator lights are off.
The following factors can cause the power supplies to overheat:
v An unusually high room temperature
v Fan failures in the power supply and fan units
v Defective circuitry in the power supply
v Blocked air vents
v Failures in other devices in the configuration or cabinet
v Dirty filter in the Telco bezel
If a fan failure causes overheating or the operating environment becomes too hot
(greater than 55° C), the Global Fault LED on the storage expansion enclosure
turns on. The power supply and fan unit Fault and Service Action Allowed (SAA)
LEDs on the back of the storage subsystem also turn on. “Controller LEDs” on page
129 shows the location of these LEDs.
Attention: Because the power supply and fan unit CRU Fault and SAA LEDs are
lit when the operating environment temperature is too hot (greater than 55° C), do
not assume the power supply and fan unit CRU is bad. Take action to cool down
the environment first. When the operating environment temperature is within the
specified operating environment range, the power supply and fan unit Fault and
SAA LEDs will be unlit if there are no problems with the power supply and fan unit
CRU.
138 IBM System Storage DS4700 Express Storage Subsystem: Installation, User’s and Maintenance Guide