[ TIP OF THE DAY ] VMware vMotion operation fails at 14%.

While performing VMware vMotion, the operation fails at 14%. What could be the possible reasons? One reason could be If your management network and vMotion network are in the same subnet using the same physical NIC, and you have assigned a VLAN id to the vMotion network, then this operation will fail. Avoid using same IP subnet for both management and vMotion networks. Because if you use the same subnet, all the vMotion traffic will be forwarded to the physical NIC connected to the management network.

By default all traffic from VMkernel port-groups from the same subnet will be forwarded to the first NIC configured in the ESXi for that IP subnet. Obviously this will be the management network. So, What happens when we assign a VLAN to the vMotion portgroup? vMotion vmknic will try to communicate with the default gateway and since the default gateway is not tagged with the VLAN id you choose for vMotion, the operation fails.