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What is Chassis Management Controller in UCS



The Chassis Management Controller (CMC) resides in the 2100 series fabric extender module which sits inside the 5100 series blade chassis. The CMC, UCS manager, and blade BMCs work together to manage a group of up to eight processing blades in a UCS chassis. From the overall UCS architecture perspective the CMC itself is not an independent point of management; instead the CMC acts at the direction of UCS manager.

The CMC performs various tasks including:

a) Chassis discovery.

b) Chassis Power and Thermal management.

c) Hot-swap functionality support for fans, power supplies, blades, etc.

d) Chassis, Fan and Fabric extender LED control.

e) Power-on Self Test and online health monitoring.

f) Access to the chassis SEEPROM for Read/Write functionality.

g) Local cluster management.


CMC functioning Overview

The CMC runs its own software and reports the error messages as well as other information to the UCS manager via IPMI. The CMC starts running as soon as the UCS chassis is powered up. If there is only one fabric extender module in the UCS chassis then the CMC on that fabric extender takes the ownership of the entire UCS chassis. If there are two fabric extenders in the UCS chassis then the ownership goes on the basis of first-come first-serve; however in case of a tie the ownership goes to the fabric extender in slot 1. Note that the ownership is established when the link between the 6100 series fabric extender and the corresponding fabric extender becomes active. This kind of polling is required so as to establish which CMC computes thermal and power states to the UCS manager and can be used by clients for exclusive hardware control.

Chassis decommissioning is performed when a chassis is physically present and connected but you want to temporarily remove it from the configuration. Because it is expected that a decommissioned chassis will be eventually recommissioned, a portion of the chassis' information is retained by Cisco UCS Manager for future use. Removing is performed when you physically remove a chassis from the system. Once the physical removal of the chassis is completed, the configuration for that chassis can be removed in Cisco UCS Manager.

The CMC controls the fabric extender and chassis health LED behavior during the boot phase. The fabric extender health LED shows green during normal operation; shows amber during booting and blinking amber for an error. The Chassis fail LED is off if there is no error; shows amber for a minor error and shows blinking amber for major error. The CMC runs an internal algorithm to keep the thermals in the chassis at appropriate levels. It also runs the power control algorithm, which controls the power supplies, to improve the power efficiency as per the policy.


Related Information

What is BMC and what are the tasks of BMC
What are the hardware components of UCS