Path Selection Plug-Ins (PSPs) run in conjunction with the VMware NMP and are responsible for choosing a physical path for I/O requests.

The VMware NMP assigns a default PSP for every logical device based on the SATP associated with the physical paths for that device. You can override the default PSP.

By default, the VMware NMP supports the following PSPs:

Most Recently Used (MRU)

Selects the path the ESX/ESXi host used most recently to access the given device. If this path becomes unavailable, the host switches to an alternative path and continues to use the new path while it is available.


Uses the designated preferred path, if it has been configured. Otherwise, it uses the first working path discovered at system boot time. If the host cannot use the preferred path, it selects a random alternative available path. The host automatically reverts back to the preferred path as soon as that path becomes available.


With active-passive arrays that have a Fixed path policy, path thrashing might be a problem.

Round Robin (RR)

Uses a path selection algorithm that rotates through all available paths enabling load balancing across the paths.