cmSysRedundancy is a read-write enumeration controlling whether the secondary SCM is permitted to take over as primary if the primary fails. An administrator sets it to enabled(2) on chassis equipped with a redundant SCM pair to enable automatic failover protection, or reads notAvailable(3) to know the hardware simply doesn't support redundancy. For example, on a chassis with only one SCM installed, cmSysRedundancy would read notAvailable, telling the operator that manually replacing that card during a fault will cause a service outage.