IBM System Storage Subsystem DS5020 - Manual (Page 170)

units 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 112.
Attention: The fans in the power supply and fan units draw in fresh air and force
out hot air. The power supply and fan units are hot-swappable and redundant;
however, if the fans in one power supply and fan unit fail, you must replace the
entire failed power supply and fan unit within 72 hours to maintain redundancy and
optimum cooling. Do not remove the failed power supply and fan unit until you have
the replacement power supply and fan unit. When you do remove the failed power
supply and fan unit, be sure to install the second power supply and fan unit within
10 minutes to prevent any overheating due to the interruption to the air flow that
cools the storage subsystem.
Do not run the storage subsystem without adequate ventilation and cooling,
because it might cause damage to the internal components and circuitry.
Use the following procedure to replace an ac power supply and fan unit. Figure 83
on page 143 illustrates removing and inserting a unit.
Attention: Potential damage to a component - To prevent damage from
overheating, replace a failed power supply and fan unit CRU within 15 minutes of
removal. If replacing it will take longer than 15 minutes, stop all I/O activity to the
storage subsystem and turn off the power until you complete the replacement.
Statement 8:
CAUTION:
Never remove the cover on a power supply and fan unit or any part that has
the following label attached.
Hazardous voltage, current, and energy levels are present inside any
component that has this label attached. There are no serviceable parts inside
these components. If you suspect a problem with one of these parts, contact
a service technician.
1. If needed, use the DS Storage Manager client software to print a storage
system profile.
2. Did the Recovery Guru direct you to replace a failed power supply and fan
unit?
v Yes - Go to step 3.
v No - Run the Recovery Guru to identify the failed component, and then go
to step 3.
3. Put on antistatic protection.
140 IBM System Storage DS5020 Storage Subsystem: Installation, User’s, and Maintenance Guide