IBM TotalStorage DS4400, User Manual

Page: 87 / 124

Power supply
The DS4400 Storage Server power system consists of two power supplies. The
power supplies slide into either of the two slots on the back of the DS4400 Storage
Server. The power supplies provide power to the internal components by converting
incoming ac voltage to dc voltage. The power supplies are interchangeable and
redundant. Each power supply uses one power cord. You can plug both power
cords into a common power source or plug each cord into a separate circuit for
power redundancy. One power supply can maintain electrical power to the DS4400
Storage Server if the other power supply is turned off or malfunctions.
Servicing notes
Consider the following when servicing the power supplies:
v Each power supply has a built-in sensor that detects the following conditions:
– Overvoltage
– Overcurrent
– Overtemperature
If any of these conditions occur, one or both power supplies enter shutdown
mode. All power remains off until one of the following occurs:
– You cycle the power switches (turn off the power switches, wait at least 30
seconds, then turn on the power switches). For more information, see
“Overtemperature condition and power supply shutdown” on page 36.
– The power supplies automatically resume operation when the ambient air
temperature cools to below 70° C (158° F). When the power supplies
automatically resume operation, the DS4400 Storage Server also resumes
operation.
v You can hot swap (replace) a power supply because the two power supplies
provide redundancy.
v
Both power supplies have built-in temperature sensors designed to prevent the
power supplies from overheating. If a temperature sensor detects an ambient air
temperature greater than 70° C (158° F), the “overheated” power supply
automatically shuts down. The second power supply remains on as long as its
temperature remains below 70° C (158° F). If the second power supply
overheats, it turns off all power to the DS4400 Storage Server.
Note: There is a serious problem if the air temperature inside the rack cabinet is
hot enough to cause the power supplies to shut down.
v The DS4400 Storage Server is capable of power-up recovery without operator
intervention. Once the air temperature cools to below 70° C (158° F), the power
supplies automatically restart. An automatic restart resets the controllers,
attempts to restart the hard disk drives, which has no effect on the hard disk
drives if they are already running, and returns the DS4400 Storage Server to
normal operation.
v When a power supply fails, the green power indicator light on the power supply
goes off and the amber power supply fault light is lit on the front of the DS4400
Storage Server. For more information, see “Power supply indicator light” on page
33 and “Storage server indicator lights” on page 28.
v If you replace the power supply CRU and still experience problems, the DS4400
Storage Server might have defective components or connections. Check the
storage-management software for indications of other component failures.
Chapter 3. Replacing DS4400 Storage Server components
55