An administrator needs to configure Network IO Control (NIOC) on a Virtual Distributed Switch (VDS)...

Network IO Control (NIOC) must be enabled on the Virtual Distributed Switch (VDS) via the vSphere Client to begin configuring and managing bandwidth allocation and prioritization for different types of traffic.

After enabling NIOC, you can assign shares and limits to the specific port group (in this case, for storage traffic) to prioritize the traffic over other types of network traffic.