Hi,
with active/passive: one controller is doing all the work (CPU, protocols, etc) and the partner just wait to take control in case of failure.
in this case, almost all disks are owned by the active controller.
with active/active: both controllers are working, each one serve its own data (volumes).
in this case, all disks needs to be divided to both controllers.
in order to decide what is best configuration for your ENV, it is recommended to do sizing with NetApp partner.
good luck,
Ariel
