What is a system called that duplicates resources to improve reliability?

A system designed to duplicate resources to enhance reliability is known as a redundant system. This approach involves creating additional copies of critical components or subsystems, ensuring that if one fails, the other can take over, thereby preventing service disruption. Redundancy is a crucial principle in system design, particularly in environments where uptime and reliability are paramount, such as in data centers or critical applications.

While backup systems are essential for data recovery, they typically refer to copying data for restoration rather than providing immediate redundancy in resource availability. Load balancing systems distribute workloads across multiple resources to optimize performance but do not inherently provide redundancy. Fault-tolerant systems are closely related and are designed to continue operating despite failures; however, they often employ redundancy as part of their functionality. In summary, a redundant system specifically focuses on duplicating resources to ensure that the system remains operational even in the event of a failure, making it the most accurate answer in this context.