Unisphere and Unisphere Central 2020 R1 Administrator's Guide

ALUA Port Mode

Asymmetric Logical Unit Access (ALUA) provides port and controller redundancy for SAS front-end connections.

Volumes mapped to a server using SAS front-end also have port and controller redundancy. Volumes mapped over SAS are mapped to both controllers. The volume mapping is Active/Optimized on one controller and Standby on the other controller. If the port or controller fails on the active controller, the paths to the other controller become Active/Optimized. The mapping on the first controller switches to Standby. When the port or controller recovers, the mapping to the first controller returns to Active/Optimized and the mapping to the second controller returns to Standby status.