ESXi hosts can use multipathing for failover. With some storage devices, ESXi hosts can also use multipathing for load balancing.

To achieve better load balancing across paths, administrators can specify that the ESXi host should switch paths under specific circumstances. Different options determine when the ESXi host switches paths and what paths are chosen. Only a limited number of storage arrays support round robin.

You can use esxcli storage nmp psp roundrobin to retrieve and set round robin path options on a device controlled by the roundrobin PSP. Specify one of the options listed in Connection Options for vCLI Host Management Commands in place of <conn_options>.

No vicfg- command exists for performing the operations. The ESXCLI commands for setting round robin path options have changed. The commands supported in ESXi 4.x are no longer supported.

Procedure
1

Retrieve path selection settings for a device that is using the roundrobin PSP. 

esxcli <conn_options> storage nmp psp roundrobin deviceconfig get --device na.xxx
2

Set the path selection. You can specify when the path should change, and whether unoptimized paths should be included.

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Use --bytes or --iops to specify when the path should change, as in the following examples. 

esxcli <conn_options> storage nmp psp roundrobin deviceconfig set --type "bytes" -B 12345 --device naa.xxx

Sets the device specified by --device to switch to the next path each time 12345 bytes have been sent along the current path. 

esxcli <conn_options> storage nmp psp roundrobin deviceconfig set --type=iops --iops 4200 --device naa.xxx

Sets the device specified by --device to switch after 4200 I/O operations have been performed on a path.

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Use useano to specify that the round robin PSP should include paths in the active, unoptimized state in the round robin set (1) or that the PSP should use active, unoptimized paths only if no active optimized paths are available (0). If you do not include this option, the PSP includes only active optimized paths in the round robin path set.