IPMI

IPMI ( Intelligent Platform Management Interface ) : It is a remote hardware health monitoring and management system that defines interfaces for use in monitoring the physical health of servers.

IPMI provides a way to monitor & manage a server system that may be powered off or unresponsive by using a network connection to the hardware rather than to an OS.

IPMI functions independently of the OS to allow system admins to manage a system remotely in the absence of an operating system .IPMI can work in any of three situations:
Situation 1 : Your remote server is down, the Operating System is not booting up and you need to check what happened remotely and you need to start the machine, again remotely (without accessing the physical hardware).

Situation 2 : You are on a weekend holiday and you received email that one node in cluster is not responding. You need to find what happened and might need to fence (or reboot) the machine, remotely.

Situation 3 : You need a detailed report on server health.

The primary IPMI features include:

Monitoring (supervision of the hardware)
Recovery Control (Recover/Restart the server)
Logging (protocol “out-of-range” states for the hardware)
Inventory (list of hardware inventory)
IPMI provides these four functions independently from the server’s CPU, BIOS and operating system. The platform management features are also available when the server has been shutdown (as long as at least one server power supply has power).