round-robin path switching trigger type

[MMAgeek]

Hi, whilst browsing the new esxcli documentation i found this info:

storage nmp psp roundrobin deviceconfig set 

--type | -t

Set the type of the Round Robin path switching that should be enabled for this device. Valid values for type are: bytes: Set the trigger for path switching based on the number of bytes sent down a path. default: Set the trigger for path switching back to default values. iops: Set the trigger for path switching based on the number of I/O operations on a path.

The option to set the trigger for path switching based on the number of bytes sent down a path, is this new and is there any more information on this? When would i want to use this instead of setting using the older IOPs switching?

Thanks