Migrations

One way that Hyper-V Server offers high availability is through its Live Migration feature. This technology allows a running virtual machine to transfer from one physical host to another without incurring downtime. There is a brief interruption as the logical network components make the transition and MAC addresses are relocated on switching hardware, but the transfer occurs within the standard TCP timeout window. Any lost TCP packets will be retransmitted, while any lost UDP packets will be simply lost as UDP is not a guaranteed lossless protocol. Other protocols will behave according to their design; ICMP packets (such as ping), will also be lost as ICMP's purpose is to check for network issues. For some applications, such as real-time voice communications (for example, Microsoft Lync Server), this can cause an interruption of service. For most, it does not affect availability in a way that would count as downtime in an SLA. Therefore, Live Migration contributes to high availability...