What does an Active/Optimized path mean in a FAS configuration?

In a traditional FAS SAN configuration, ONTAP uses ALUA to distinguish optimized paths from non-optimized paths. Active/Optimized paths are serviced by the controller associated with the aggregate and LUN being accessed. These paths provide the preferred I/O route because data does not need to be forwarded through another controller. Paths through the HA partner remain available but are normally Active/Non-Optimized and are used when optimized paths become unavailable. NetApp host configuration guidance explicitly describes AFF and FAS systems as having higher-priority Active/Optimized paths serviced by the controller where the aggregate resides and lower-priority non-optimized paths served through another controller. Round-robin is a host multipathing policy and does not define ALUA path state. Relevant topics include ALUA, Active/Optimized paths, Active/Non-Optimized paths, FAS multipathing, and HA architecture.