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24 MPCMM0001 Chassis Management Module Software Technical Product Specification
Redundancy, Synchronization, and Failover
upgrade: Synchronizes user scripts only when the other CMM has a newer firmware version.
downgrade: Synchronizes user scripts only when the other CMM has an older firmware version.
always: Synchronizes user scripts irrespective of version differences.
3.3.2.2 Retrieving User Scripts Sync Configuration Flag
To retrieve the value of the Scripts Synchronization configuration flag, the following CMM
command is used:
cmmget -l cmm -d syncuserscripts
The value returned will be one of: Equal, Upgrade, Downgrade, Always, or Error on failure.
3.3.3 Synchronization Requirements
For synchronization to occur:
• The CMMs must be able to communicate with each other over their dedicated IPMB. The
CMMs use a heartbeat via their dedicated IPMB to determine if they can communicate with
each other over IPMB.
• An Ethernet connection must exist between the two CMMs. The CMMs must be able to ping
each other via Ethernet for synchronization to be successful. This can be a connection through
the Ethernet switches in the chassis, which requires both switches to be present in the chassis;
a connection can occur through an external Ethernet switch connected to the front ports of the
CMM pair, or alternatively, the connection can be a crossover cable connecting the two front
ports of the CMM pair. If synchronization fails on eth1, then it will be attempted on eth0. If the
CMMs cannot successfully ping each other via eth0 or eth1, then synchronization between the
CMMs cannot occur.
A failure of any priority 1 synchronization will result in a health event being logged in the CMM
SEL and will inhibit a failover from occurring.
3.4 Initial Data Synchronization
It is absolutely necessary that a standby CMM has the priority one files synched before a successful
failover can occur. A standby CMM can still become active if all priority one synchronization has
not been completed, but it may not be able to properly manage all the FRU’s in the chassis.
The CMM implements the “Datasync Status” sensor to determine the state of synchronization and
if synchronization has completed. successfully.
3.4.1 Initial Data Sync Failure
If CMM encounters any failure during data synchronization it marks the data synchronization
failure and logs a SEL event and sends an SNMP trap. Duplicate failures are not reported multiple
times. As soon as CMM is out of failure condition it will reset data synchronization failure state.
The CMM will continue trying to synchronize as long as there are two CMMs present in the
chassis and they are able to communicate via their cross-connected IPMB.