Lights Out Management (LOM) is Apple's implementation of the remote monitoring and management protocol Intelligent Platform Management Interface (IPMI) developed by Intel.
The addition of Lights Out Management to Xserve provides for the monitoring of over 100 sensors that measure voltage, temperature, fan speeds, etc. Using Server Monitor, one can get a fairly complete picture of the health of an Xserve.
In addition to monitoring LOM can also be used to control some functions of an Xserve. Xserve can be shutdown or restarted from a remote location via the implementation of LOM in Server Monitor. Even if the Xserve is in an unresponsive state, one should be able to gain access via LOM.
The LOM process is controlled by a dedicated processor. This processor works independently of the two Xeon processors in the Xserve, leaving them to focus on server tasks.
The LOM processor is accessed through one or both of the built-in Ethernet ports. Each built-in Ethernet port has two MAC addresses assigned: One is dedicated to the LOM processor, the other is used by Mac OS X Server. This means there are two MAC addresses accessible by Mac OS X Server, and two dedicated to the LOM processor.
During the setup process, IP addresses are assigned to one and/or both MAC addresses reserved for the LOM processor. These IP addresses used by the server and the IP addresses used by the LOM processor must be different. Additionally, an account is created to access the LOM processor. This account is used to access LOM features and data but is not used in any other part of the system.
To manage LOM access (IP addresses and account information), use Server Monitor. This is the only location, outside of the setup assistant, where this information can be accessed. The LOM account will not show up in Workgroup Manager, nor will the LOM interface be visible in System Preferences. For more information on managing LOM access, see Server Monitor Help.
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