Redundancy refers to the presence of duplicated systems, components, hardware or software. These can be put into operation if the primary system fails or malfunctions. The purpose of redundancy is to ensure the continuity of business processes and that systems continue to operate when a failure occurs; another system then ensures continuity in operation.
Redundancy can be achieved in various ways. At server level in a data center, multiple identical hard drives can be provided. Also, double network connections, backup power supplies (such as an uninterruptible power supply or UPS), or even complete data centers that can function geographically separated as backup for each other can be considered.
See Emergency plan