What is the difference between Active, Active, and ALUA in VNX?

In Active/Active mode, all paths are available at the same time. When path or SP is faulty, or NDU, the LUN trespass is no longer needed to be mounted to another SP, so there is no latency and the system reliability is increased. At the same time, because I/O can pass all the paths, the performance has been doubled.

ALUA, however, only the active/optimized path can pass through I/O, while the other active/non-optimized path host can see the LUN but will not pass through I/O. If path or SP is faulty, the LUN will send a trespass to another SP.