There are three Multipathing Policies available in ESXi server:
•Most Recently Used (MRU): Selects the first working path discovered at system boot time. If this path becomes unavailable, the ESXi host switches to an alternative path and continues to use the new path while it is available. This is the default policy for LUNs presented from an Active/Passive array.
•Fixed (Fixed): Uses the designated preferred path, if it has been configured. Otherwise, it uses the first working path discovered at system boot time. If the ESXi host cannot use the preferred path, it selects a random alternative available path. The ESXi host automatically reverts back to the preferred path as soon as the path becomes available. This is the default policy for LUNs presented from an Active/Active array.
•Round Robin (RR): Uses an automatic path selection rotating through all available paths and enabling the distribution of the load across the paths. For Active/Passive arrays, only the paths to the active controller will used in the round robin. For Active/Active arrays, all paths will used in the round robin. This policy is not currently supported for LUNs that are part of a Microsoft Cluster Service (MSCS) virtual machine.