active redundancy

This term is defined in ECSS-Q-ST-30-02C as
redundancy wherein all means for performing a required function are intended to operate simultaneously [IEC 60050-191]

This term is defined in ECSS-Q-ST-30-09C as
every entity is operating and the system can continue to operate without downtime or defects despite the loss of one or more entities

This term is defined in ECSS-S-ST-00-01C as
redundancy where all entities are operating and the system can continue to operate without downtime or defects despite the loss of one or more entities