IBM DS4800 - Replacing a Power Supply-Fan

should schedule the upgrade during a non-peak I/O (low-usage) period. Use the
DS4800 Storage Manager performance monitor function to determine the
non-peak I/O load time if required.
v Cold-case upgrade procedure — The DS4800 storage subsystem is powered
down when controllers are upgraded.
Note:
The cold-case controller upgrade procedure is recommended if your
production environment allows the scheduling of downtime for
maintenance purposes.
Refer
to the IBM System Storage DS4800 Controller Upgrade Kit Instructions for
step-by-step instructions for upgrading DS4800 controller cache.
Replacing a power supply-fan
The power supply-fan is a component that includes both a 400-W power supply unit
and two fans. The power supply-fans provide power and cooling for the DS4800
Storage Subsystem. The power supply-fans are customer replaceable units (CRUs)
and do not require preventive maintenance. Use only the supported power
supply-fan units for your specific storage subsystem.
Each power supply-fan has a built-in sensor that detects the following conditions:
v Over-voltage
v Over-current
v Overheated power supply
If
any of these conditions occurs, one or both power supplies will shut down. If the
power remains off after the condition that causes it to go off, make sure that the
environment is optimal (no overheating has occurred, all electrical outlets are
working, and so on). For more information, see “Restoring power after an
unexpected shutdown” on page 102.
The storage subsystem cooling system consists of two fans in each of the two
power supply-fans. The power supply-fans circulate air from the front to the back of
the unit.
If both power supply-fans fail, or if the power supply-fans cannot maintain an
internal temperature below 70° C (158° F), the power supply-fans in the unit will
automatically shut down (an over-temperature condition). If this occurs, you must
cool the unit and restart it. See “Restoring power after an unexpected shutdown” on
page 102.
Attention: The fans in the power supply-fan units draw in fresh air and force out
hot air. The power supply-fan units are hot-swappable and redundant; however, if
the fans in one power supply-fan unit fail, you must replace the entire failed power
supply-fan unit within 48 hours to maintain redundancy and optimum cooling. Do
not remove the failed power-supply fan unit from the DS4800 chassis until you have
the replacement power supply-fan unit. When you do remove the failed power
supply-fan, be sure to install the second power supply-fan within 10 minutes to
prevent any overheating due to the interruption to the air flow that cools the
DS4800 chassis.
Do not run the storage subsystem without adequate ventilation and cooling,
because it might cause damage to the internal components and circuitry.
144 IBM System Storage DS4800 Storage Subsystem: Installation, User’s, and Maintenance Guide