IBM DS4700 manual Recovering from an overheated power supply and fan unit

the appropriate DS4000 Storage Subsystem Installation, User's, and Maintenance Guide during any attended power-up procedure.

vA 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:

vAn unusually high room temperature

vFan failures in the power supply and fan units

vDefective circuitry in the power supply

vBlocked air vents

vFailures in other devices in the configuration or cabinet

vDirty 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.

138IBM System Storage DS4700 Express Storage Subsystem: Installation, User’s and Maintenance Guide