What is NPAR?
NPAR (NIC Partitioning) provides the capability to create multiple native Ethernet interfaces that share a single physical port.
What is SR-IOV?
SR-IOV (Single Root – IO Virtualization) is a standard that can present single PCIe device (this is called Physical Function) as multiple independent PCIe devices (each one is called Virtual Function) to Operating Systems and hypervisors.
NPAR and SR-IOV are the technologies that provide IO virtualization capabilities, however they do so in different ways.
This blog captures high level capabilities of NPAR and SR-IOV in VMware ESXi .
NPAR | SR-IOV |
NPAR is specific to a Server OEM. | SR-IOV is a PCI SIG standard. |
Implemented at hardware layer. | SR-PCIM (Single Root – PCI Manager) has to be implemented at Hypervisor level. |
On a dual port adapter, each physical port is partitioned into 4 physical functions and each of the 4 partitions is an actual PCI Express function. | On a dual port adapter, each physical port is further partitioned into multiple virtual functions. We can create maximum of 641 virtual functions per port. |
On a dual port adapter, if NPAR enabled on port 0 the same setting is inherited to port 1 as well. | On a dual port adapter, We have to enable the virtual functions on each port based on the requirement. |
NIC Partitions are separate physical functions and same NIC driver exposes all the physical functions. | Virtual functions are associated with a physical function and it requires Virtual Function (VF) driver at Guest OS level. |
We can allocate flexible bandwidth to each physical function. | A virtual function doesn’t have the capability to allocate bandwidth. |
1. SR-IOV supports up to 43 virtual functions on supported Intel NICs and up to 64 virtual functions on supported Emulex NICs. The actual number of virtual function available for pass-through depends on number of interrupts vectors required by each of them.
NOTE: Please consider networking configuration maximums, when enabling NPAR or SR-IOV in VMware vSphere environment.
http://www.vmware.com/pdf/vsphere5/r55/vsphere-55-configuration-maximums.pdf
Other references:
http://en.community.dell.com/techcenter/b/techcenter/archive/2012/10/26/sr-iov-and-vmware-esxi.aspx
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