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MPCMM0001 Chassis Management Module Software Technical Product Specification 39
Re-enumeration
Re-enumeration 5
5.1 Overview
The Chassis Management Module has the ability to re-enumerate devices in the chassis in the event
that the chassis loses and then regains CMM management. This allows the CMM to query
information on all devices in the chassis on startup if there are no active CMMs in that chassis
already containing that information from which it can receive via a regular synchronization. This is
achieved without having to restart the individual blades already present in the chassis.
Re-enumeration provides a way to recover from situations such as double failures where both the
CMMs have failed or been accidentally removed from the chassis. For the CMM to identify the
contents of the chassis, it first determines if it should do this function. The Standby CMM does not
re-enumerate its information and relies on the information synchronized from the Active CMM in
case a failover occurs. After the startup, the Active CMM determines what Entities are present.
Then for each of these Entities, the CMM queries it to get state and other information to be able to
properly manage the Entity as well as the entire chassis. The CMM stays in M2 state until re-
enumeration is complete.
The CMM re-enumeration process obtains the following information for each FRU in the chassis:
—Presence
— M-State
— Power Usage
— Sensor Data Records
— Health Events
— Board EKey Usage
— Bused EKey Usage
5.2 Re-enumeration on Failover
In case of forced failover, the newly Active CMM will do re-enumeration if following conditions
are satisfied:
• Re-enumeration has not completed on the Active CMM.
• Active CMM has not yet synchronized the re-enumerated data over to the Standby CMM.
In case the newly Active CMM has to do re-enumeration, it will switch to M2 state before starting
re-enumeration. The Blue LED uses long blinks to provide visual indication of the state of the
CMM. It is recommended that the Entities in the chassis be not activated or deactivated while re-
enumeration is in progress.