Hyper-V, Server 2012 / R2, Server 2016, Virtualization

Enabling SR-IOV on VMs

The single root I/O virtualization (SR-IOV) interface is an extension to the PCI Express (PCIe) specification. SR-IOV allows a device, such as a network adapter, to separate access to its resources among various PCIe hardware functions. SR-IOV enables network traffic to bypass the software switch layer of the Hyper-V virtualization stack. Because the VF is assigned to a child partition, the network traffic flows directly between the VF and child partition. As a result, the I/O overhead in the software emulation layer is diminished and achieves network performance that is nearly the same performance as in nonvirtualized environments.

Technically, there are two functions implemented by SR-IOV: physical functions (PFs) and virtual functions (VFs). There are a number of PCI devices available in which the PFs have been implemented, but Microsoft Hyper-V provides SR-IOV support only for networking. In other words, Microsoft Hyper-V provides VFs to allow VMs to communicate to the physical network adapters directly. Since the VMs can communicate directly with the physical network adapters, organizations may benefit from increasing I/O throughput, reducing CPU utilization on Hyper-V hosts for processing network traffic, and reducing network latency by enabling direct communication. Before you can use SR-IOV for a Hyper-V VM, you will need to meet the following prerequisites:

  • The SR-IOV functionality is currently only available to Windows 8 and Windows Server 2012 guests.
  • Hyper-V must be running on a Windows Server 2012 or later operating system.
  • You must have an SR-IOV-capable physical network adapter that implements the PFs and can understand the VFs’ requests coming from the VMs.
  • You must have an external virtual switch that can understand the SR-IOV traffic.
  • The server’s motherboard chipset must also support SR-IOV.

Enabling SR-IOV is a two-step approach. First, you need to create an external switch and enablecSR_IOV or if there is one already created but SR-IOV not enabled, you will need to delete this as this can only be enabled while you are creating the switch. Once the SR-IOV is enabled on the external virtual switch, you can enable SR-IOV on the VMs by checking the “Enable SR-IOV” checkbox found under the “Hardware Acceleration” under Network Adapter settings on the VM’s properties.

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Networking / Infrastructure, Server 2012 / R2, Server 2016, Virtualization

RDMA and SMB Direct

Remote Direct Memory Access (RDMA) is a technology that allows data to be written directly on tot he memory without involving the processor, cache or operating system. RDMA enables more direct data movement in and out of a server by implementing a transport protocol in the network interface card NIC. The technology supports a feature called zero-copy networking that makes it possible to read data directly from the main memory of one computer and write that data directly to the main memory of another computer.

  • Enabled by default in Windows Server 2016

  • RDMA capable network adapter

  • RDMA and SMB Multichannel must be enabled and running

  • Best used with 10 gigabit plus networks

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SMB Direct is SMB over RDMA.

Network adapters that have RDMA can function at full speed with very low latency, while using very little CPU. For workloads such as Hyper-V or Microsoft SQL Server, this enables a remote file server to resemble local storage. SMB Direct includes:

  • Increased throughput: Leverages the full throughput of high speed networks where the network adapters coordinate the transfer of large amounts of data at line speed.
  • Low latency: Provides extremely fast responses to network requests, and, as a result, makes remote file storage feel as if it is directly attached block storage.
  • Low CPU utilization: Uses fewer CPU cycles when transferring data over the network, which leaves more power available to server applications.

Requires
– Two servers running Windows Server 2012 or later
– One or more network adapters with RDMA capability
– Disabling SMB multichannel and RDMA disables SMB direct

Hyper-V, Server 2016, Virtualization

Server 2016 – Receive Side Scaling – RSS

RSS enables network adapters to distribute the kernel-mode network processing load across multiple processor cores in multi-core computers. The distribution of this processing makes it possible to support higher network traffic loads than would be possible if only a single core were to be used. In Windows Server 2012, RSS has been enhanced, including computers with more than sixty-four processors. RSS achieves this by spreading the network processing load across many processors and actively load balancing TCP terminated traffic.

When enabled, an network adapter I/O queue uses more than a single processor
core
If not enabled, uses a single core
– VMMQ has multiple queues and cores
– RSS older technology, but doesn’t have rigorous hardware requirements
Can be enabled on physical NIC (RSS)
Can be enabled on virtual NIC (vRSS)

You can use Virtual Receive Side Scaling (vRSS) to configure a virtual network adapter to load balance incoming network traffic across multiple logical processor cores in a VM or multiple physical cores for a host virtual Network Interface Card (vNIC).+

This configuration allows the load from a virtual network adapter to be distributed across multiple virtual processors in a virtual machine (VM), allowing the VM to process more network traffic more rapidly than it can with a single logical processor.

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Load balance incoming network traffic across multiple virtual processors
With RSS it is physical network adapters and physical processor cores
– With vRSS it is Hyper-V network adapters and virtual processor cores
   vRSS requires that physical network adapters support VMQ
– Can’t use vRSS without VMQ capable adapters
– Run Get-NetAdapterVMQ as administrator to check if adapter supports VMQ

Hyper-V, Server 2016, Virtualization

Server 2016 – Virtual Machine Multi Queues – VMMQ

Virtual Machine Device Queues (VMDq) is a technology that allows the network adapter to create multiple separate queues, distributing the processing load across multiple cores.

Without VMDq, traffic is processed by a single processing core. Incoming traffic is processed in the following sequence on a physical adaptor linked to a virtual switch with many virtual machines .

  • VMMQ allows multiple I/O queues on network adapters to map to multiple virtualprocessor cores on VMs

  • Each I/O queue has an affinity with a specific virtual processor core

  • Once enabled on physical NIC, enable in hardware acceleration section of virtualNIC

  • VM must be assigned multiple virtual cores to take advantage of VMMQ

Run Get-NetAdapterVMQ as Administrator to verify if adapter supports VMQ

 

Hyper-V, Server 2016, Virtualization

Server 2016 – SMB Multi-channel

SMB Multichannel, a feature included with Windows Server 2012 R2 and Windows Server 2012 and part of the Server Message Block (SMB) 3.0 protocol, increases the network performance and availability of file servers.

SMB Multichannel enables file servers to use multiple network connections simultaneously. It facilitates aggregation of network bandwidth and network fault tolerance when multiple paths are available between the SMB 3.0 client and the SMB 3.0 server. This capability allows server applications to take full advantage of all available network bandwidth and makes them resilient to network failures.

SMB Multichannel provides the following capabilities:

  • Increased throughput. The file server can simultaneously transmit additional data by using multiple connections for high-speed network adapters or multiple network adapters.
  • Network fault tolerance. When clients simultaneously use multiple network connections, the clients can continue without interruption despite the loss of a network connection.
  • Automatic configuration. SMB Multichannel automatically discovers multiple available network paths and dynamically adds connections as necessary.

REQUIREMENTS; 

SMB Multichannel has the following requirements:

  • At least two computers that run on Windows Server 2012 R2, Windows Server 2012, or Windows 8 operating systems are required. No additional features have to be installed—SMB Multichannel is enabled by default.
  • At least one of the following configurations:
    • Multiple network adapters
    • One or more network adapters that support Receive Side Scaling (RSS)
    • One of more network adapters that are configured by using NIC Teaming
    • One or more network adapters that support remote direct memory access (RDMA)

So,

  • Use all available NIC in a computer to share file sharing load
  • Does not require NICs to be on the same subnet
  • SMB 1 and SMB 2 clients use a single NIC connection to retrieve files

SMB Multichannel provides the following capabilities:

  • Increased throughput. The file server can simultaneously transmit additional data by using multiple connections for high-speed network adapters or multiple network adapters.
  • Network fault tolerance. When clients simultaneously use multiple network connections, the clients can continue without interruption despite the loss of a network connection.
  • Automatic configuration. SMB Multichannel automatically discovers multiple available network paths and dynamically adds connections as necessary.
Hyper-V, Server 2016, Virtualization

Server 2016 – Switch Embedded Teaming

SET is an alternative NIC Teaming solution that you can use in environments that include Hyper-V and the Software Defined Networking (SDN) stack in Windows Server 2016. SET integrates some NIC Teaming functionality into the Hyper-V Virtual Switch.+

SET allows you to group between one and eight physical Ethernet network adapters into one or more software-based virtual network adapters. These virtual network adapters provide fast performance and fault tolerance in the event of a network adapter failure.

Windows Server 2012 R2 doesn’t allow RDMA on NIC bound to NIC team or Hyper-
V virtual switch. Windows Server 2012 R2 required 2 sets of NIC, one for RDMA, one for regular IP.

SET allows one set of switches to be used for Hyper-V vSwitch with RDMA.
NICs support regular IP traffic as well as RDMA.

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Server 2016, Virtualization

Server 2016 Licensing

Windows Server 2016 licensing model

The business model for Standard and Datacenter editions transitioned from processor-based to core-based licensing in October 2016 with the general availability of Windows Server 2016 (all other editions of Windows Server 2016 continue to be on the processor-based licensing model). Core-based licensing provides a more consistent licensing metric across environments, enabling multicloud environments, improving workload portability for Windows Server through benefits like Azure Hybrid Use Benefit (AHUB), and helping remove friction across different licensing models.

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Customers with Software Assurance will transition to core-based licensing at their first renewal after the general availability of Windows Server 2016, although they can deploy Windows Server 2016 at any time.

The Windows Server 2016 licensing model includes both Cores + Client Access Licenses (CALs). Each user and/or device accessing a licensed Windows Server Standard, Datacenter, or Multipoint edition requires a Windows Server CAL or Windows Server and Remote Desktop Services CAL. A Windows Server CAL gives a user or device the right to access any edition of Windows Server of the same or earlier version. Each Window Server CAL allows access to multiple licenses of Windows Server.

Edition                  Licensing model       CAL requirements

Datacenter               Core-based*          Windows Server CAL**

Standard                   Core-based*           Windows Server CAL**

Essentials                 Specialty server      No CAL required 

** All physical cores on the server must be licensed, subject to a minimum of 8 core licenses per physical processor and a minimum of 16 core licenses per server.

** CALs are required for every user or device accessing a server.

Windows Server 2016 Standard and Datacenter: Core-based licensing

Core-based licensing requires all physical cores in the server to be licensed. Servers are licensed based on the number of processor cores in the physical server.

• A minimum of 8 core licenses is required for each physical processor and a minimum of 16 core licenses is required for each server.

• Core licenses are sold in packs of two.*

• Standard Edition provides rights for up to 2 Operating System Environments or Hyper-V containers when all physical cores in the server are licensed. For each additional 1 or 2 VMs, all the physical cores in the server must be licensed again.

• The price of a set of 16 core licenses (for a 2-processor server) for Windows Server 2016 Datacenter and Standard editions is the same price** as the 2-processor license of the corresponding edition of Windows Server 2012 R2. Windows Server 2016 Licensing Azure Hybrid Use Benefit With the Azure Hybrid Use Benefit, customers with Software Assurance can benefit from special pricing for new Windows Server virtual machines in Azure. Customers pay only for the base compute rate, which is currently the same as the Linux rate for virtual machines.

** 8 two-core packs will be the minimum required to license each physical server. The two-core pack for each edition is 1/8th the price of a license for a 2-processor server for corresponding Windows Server 2012 R2 editions.

** Rounding may result in slight variations in the final price of eight 2-pack core SKUs relative to the price of one Windows Server 2012 R2 processor SKU.

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Moving to core-based licensing

Customers purchasing net new licenses, for example, through MPSA or from an OEM, will purchase licenses under the core-based model. Existing customers with Software Assurance will transition from processor-based to core-based licensing at the first renewal after the general availability of Windows Server 2016.

• Renewal before the general availability of Windows Server 2016: Customers with Software Assurance will be on processor-based licensing and true-ups will also be processor-based.

• Renewal after the general availability of Windows Server 2016: Customers with Software Assurance will transition to core-based licensing and true-ups will also be core-based.

Core license grants overview

Customers with servers under Software Assurance will receive core license grants at the expiration of Software Assurance coverage. Depending on the core density of existing servers, there are two categories of core license grants: Full core licenses and additional core licenses.

1. Full core license grants: Customers with a server density of 8 or fewer cores per processor and 16 or fewer cores per server are eligible to receive full core license grants. Customers will receive a minimum of 8 cores per processor and 16 cores per server at the expiration of Software Assurance coverage after the general availability of Windows Server 2016. To receive full core license grants, customers do not need to document their environments.

2. Additional core license grants: Customers with a server density of more than 8 cores per processor and 16 cores per server are eligible to receive additional core license grants and pay only Software Assurance on the incremental cores. To receive additional core license grants, customers must maintain a record of the physical hardware and the configuration of the licensed server by using the Microsoft Software Inventory Logging tool (SIL) or any equivalent software. Inventory must be maintained at the first expiration of the Software Assurance coverage after the general availability of Windows Server 2016 or before September 30, 2019.

Note: Customers are not required to share inventory with Microsoft, but may be asked to share inventory if required.

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Announcing servicing guidelines for Windows Server 2016

With prior releases, Windows Server has been serviced and supported through a 5+5 model, with 5 years of mainstream support and 5 years of extended support. This model—renamed Long Term Servicing Branch (LTSB)—will continue with Windows Server 2016 for customers who choose to install full Windows Server 2016 with Desktop Experience or Server Core.

Customers choosing the Nano Server installation will opt into a more active servicing model—known as Current Branch for Business (CBB)—similar to the experience with Windows 10. This approach supports customers who are moving at a cloud cadence of rapid development lifecycles and wish to innovate more quickly. Since this servicing model continues to provide new features and functionality, Software Assurance is also required to install and use Nano Server.