Q: I read a TechNet article about Hyper-V Live Migration and Cluster Shared Volumes (CSV) that said if you only have two network adapters, you need to cap Live Migration traffic to 90 percent. How do you do this?

A: Ideally, for a Hyper-V cluster that uses Live Migration and CSV, you should have at least four network adapters; one for the virtual machine network, one for management, one for cluster traffic and CSV, and the final one for Live Migration data. If you're using iSCSI, you should have a fifth NIC for the iSCSI traffic.

If you don't have four network adapters, there are other combinations including a not-recommended combination for if you have two 1Gbps network adapters, documented on TechNet. As part of this configuration, you need to cap the Live Migration traffic to 90 percent.

The article actually describes how to perform this bandwidth cap, which you do using Quality of Service (QoS). QoS is used to place rules on bandwidth and its priority of the different types of communication over the network. Because Live Migration uses port 6600, create a QoS rule that limits TCP traffic over port 6600 to 90 percent (which is around 110MB/s on a 1Gbps link, remember the difference between Bytes and bits here). Leave the defaults for all applications and IP addresses.

To limit the management traffic you repeat the process however instead of specifying a port you limit the traffic affected to only the source IP address of the management IP address, i.e. the IP address of the actual Hyper-V host.