5.6.4.10 Network QoS and Network I/O Control
Quality of Service (QoS) can be implemented using Network I/O Control for a vSAN environment. This allows a dedicated amount of the network bandwidth to be allocated to the vSAN traffic. When using Network I/O Control, no other traffic will impact the vSAN network, and likewise, through the use of shares, other traffic types can also be protected. This is useful in a shared environment, but does require that a vSphere distributed virtual switch be used.
In Network I/O Control, configure reservation and shares for the vSAN outgoing traffic as follows:
• Set a reservation so that Network I/O Control guarantees that minimum bandwidth is available on the physical adapter for vSAN.
• Set shares so that when the physical adapter assigned for vSAN becomes saturated, certain bandwidth is available to vSAN to prevent vSAN from consuming the entire capacity of the physical adapter during rebuild and synchronization operations. For example, the physical adapter might become saturated when another physical adapter in the team fails, and all traffic in the port group is transferred to the other adapters in the team.
In addition to this, priority tagging can be set. Priority tagging is a mechanism to indicate to the connected external network devices that vSAN traffic has higher QoS demands. You can assign vSAN traffic to a certain class and accordingly mark the traffic with a Class of Service (CoS) value from 0 to 7 by using the traffic filtering and marking policy of vSphere Distributed Switch. The lower the CoS value is, the higher the priority of the vSAN data.
Figure 27. Network I/O Control
For most designs, make use of Network I/O Control and QoS when the NIC is shared between traffic types, such as if a 10-GbE network card team is used for all traffic on a host system.
