User's Manual

52 Installing and Setting Up the CMC
Primary CMC Election Process
There is no difference between the two CMC slots; that is, slot does not
dictate precedence. Instead, the CMC that is installed or booted first
assumes the role of the active CMC. If AC power is applied with two CMCs
installed, the CMC installed in CMC chassis slot 1 (the left) normally
assumes the active role. The active CMC is indicated by the blue LED.
If two CMCs are inserted into a chassis that is already powered on, automatic
active/standby negotiation can take up to two minutes. Normal chassis
operation resumes when the negotiation is complete.
Planning Deployment of Redundant CMCs
When planning CMC deployment and chassis cabling, it is recommended
that you choose the left CMC to act as the primary and the right CMC to act
as secondary, and then maintain those roles. This is best practice because it is
the default arrangement when the chassis is powered on and redundancy is
increased when all of the primary CMCs in daisy-chained chassis are cabled
together. When a failover occurs and a CMC in the right slot becomes
primary, use the RACADM cmcchangeover command to reset the CMC in
the left slot to primary.
Obtaining Health Status of Redundant CMC
You can view the health status of the standby CMC in the Web interface. For
more information about accessing CMC health status in the Web interface,
see "Viewing Chassis and Component Health Status" on page 89.