Dell PowerVault MD1120 Hardware Owner's Manual

Also see for PowerVault MD1120: Optimization guide Getting started guide Information update Setup guide Getting started guide

Contents

18 About Your SystemEnclosure Failover When Two EMMs Are InstalledIf two EMMs are installed, a certain degree of failover is offered. Control andmonitoring of the enclosure elements can be transferred from one EMM toanother in the event of an EMM failure. A failover occurs whenevercommunication is lost between an EMM and its peer.In the event of a peer EMM failure, the surviving EMM activates the amberstatus LED of the failed EMM and holds it in reset. The surviving EMM thentakes over the responsibility of enclosure management, which includesmonitoring and control of the audible alarm, enclosure LEDs, power supplies,and fans.Failover does not include providing connectivity to the physical diskscontrolled by the failed EMM. When a failed EMM is replaced, enclosuremanagement functions do not automatically return to the replaced EMMunless an additional failure occurs that triggers another failover event, or theenclosure is power cycled.EMM Thermal ShutdownIf critical internal temperatures are reached, the enclosure will be shut downautomatically via either a thermal shutdown command issued by the EMMfirmware or via a command from Server Administrator.Power Supply and Cooling Fan FeaturesYour storage enclosure supports two integrated, hot-pluggable powersupply/cooling fan modules. Each module contains four separate cooling fans.Both modules must be installed to ensure proper cooling. The enclosurerequires at least seven of the individual cooling fans to operate to avoidoverheating.CAUTION: A power supply/cooling fan module can be removed from a powered-on enclosure; however, the enclosure will shut down if overheating occurs.A power supply/cooling fan module can be replaced without powering downthe enclosure. For information on removing and replacing the modules, see"Removing and Installing the Power Supply/Cooling Fan Module" on page 35.Figure 1-7 shows the power supply/cooling fan module features and LEDindicators. Table 1-5 lists the LED indicator descriptions.