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If you want to use a storage interface that can be routed from the primary management interface also (bearing
in mind that this configuration is not the best practice), you have two options:
• After a host reboot, ensure that the storage interface is correctly configured, and use the xe pbd-unplug and
xe pbd-plug commands to reinitialize the storage connections on the host. This restarts the storage connection
and routes it over the correct interface.
• Alternatively, you can use xe pif-forget to remove the interface from the XenServer database and manually
configure it in the control domain. This is an advanced option and requires you to be familiar with how to
manually configure Linux networking.
Using SR-IOV Enabled NICs
Single Root I/O Virtualization (SR-IOV) is a PCI device virtualization technology that allows a single PCI device to
appear as multiple PCI devices on the physical PCI bus. The actual physical device is known as a Physical Function
(PF) while the others are known as Virtual Functions (VF). The purpose of this is for the hypervisor to directly
assign one or more of these VFs to a Virtual Machine (VM) using SR-IOV technology: the guest can then use the
VF as any other directly assigned PCI device.
Assigning one or more VFs to a VM allows the VM to directly exploit the hardware. When configured, each VM
behaves as though it is using the NIC directly, reducing processing overhead and improving performance.
Warning:
If your VM has an SR-IOV VF, functions that require VM mobility, for example, Live Migration,
Workload Balancing, Rolling Pool Upgrade, High Availability and Disaster Recovery, are not
possible. This is because the VM is directly tied to the physical SR-IOV enabled NIC VF. In
addition, VM network traffic sent via an SR-IOV VF bypasses the vSwitch, so it is not possible
to create ACLs or view QoS.

Assigning a SR-IOV NIC VF to a VM

Note:
SR-IOV is supported only with SR-IOV enabled NICs listed on the XenServer Hardware
Compatibility List and only when used in conjunction with a Windows Server 2008 guest
operating system.
1. Open a local command shell on your XenServer host.
2. Run the command lspci to display a list of the Virtual Functions (VF). For example:
07:10.0 Ethernet controller: Intel Corporation 82559 \
Ethernet Controller Virtual Function (rev 01)
In the example above, 07:10.0 is the bus:device.function address of the VF.
3. Assign the required VF to the target VM by running the following commands:
xe vm-param-set other-config:pci=0/0000:<bus:device.function> uuid=<vm-uuid>
4. Start the VM, and install the appropriate VF driver for your specific hardware.
Note:
You can assign multiple VFs to a single VM, however the same VF cannot be shared across
multiple VMs.
Controlling the rate of outgoing data (QoS)
To limit the amount of outgoing data a VM can send per second, you can set an optional Quality of Service (QoS)
value on VM virtual interfaces (VIFs). The setting lets you specify a maximum transmit rate for outgoing packets
in kilobytes per second.