By default, Veritas Dynamic Multi-Pathing (DMP) uses the Minimum Queue I/O policy for load balancing across paths for Active/Active (A/A), Active/Passive (A/P), Active/Passive with explicit failover (A/P-F) and Active/Passive with group failover (A/P-G) disk arrays. Load balancing maximizes I/O throughput by using the total bandwidth of all available paths. I/O is sent down the path which has the minimum outstanding I/Os.

For A/P disk arrays, I/O is sent down the primary paths. If all of the primary paths fail, I/O is switched over to the available secondary paths. As the continuous transfer of ownership of LUNs from one controller to another results in severe I/O slowdown, load balancing across primary and secondary paths is not performed for A/P disk arrays unless they support concurrent I/O.

For A/P, A/P-F and A/P-G arrays, load balancing is performed across all the currently active paths as is done for A/A arrays.

You can change the I/O policy for the paths to an enclosure or disk array.