Methods and apparatuses to restore data redundancy in a storage system with a storage virtualization engine. In one aspect of the invention, a method to restore data redundancy includes: receiving input indicating loss of redundancy for first data on a first storage unit; copying the first data from the first storage unit to a second storage unit so that the first data stored on the second storage unit has redundancy; and mapping (or configuring a storage virtualization engine to map) logical addresses for accessing the first data to physical addresses for the second storage unit in which the first data is stored. In one example according to this aspect, a portion of the second storage unit is determined and the first data is copied onto the portion of the second storage unit. The first and second storage units can be in a same storage subsystem under control of a storage controller or in different storage subsystems under control of separated storage controllers (e.g., disk controllers).