In parallel redundancy, multiple units of the same component are always active. However, only some of these units are required to be active for system operation. For example, in a one-of-two (1:2) parallel redundancy, two units are active when a particular function is performed. However, only one of these two active units is actually required for system operation. In this case, if one unit fails, the remaining unit can continue to operate, thus preventing a system failure.