Hyper-V is one of the virtualization server role in Windows Server 2012.
Virtualization servers can host multiple virtual machines that are isolated
from each other but share the underlying hardware resources by virtualizing the
processors, I/O devices and memory . By consolidating servers onto a single
machine, virtualization can progress resource usage and energy efficiency and
reduce the maintenance and operational costs of servers. In addition,the management APIs and virtual machines offer more flexibility for managing resources, provisioning systems and balancing load.
The following sectionsdefine the virtualization terminology
that is used in this guide and suggest best practices that yield increased
performance on servers running Hyper-V. Tuning guidance that can yield
increased performance on servers running Hyper-V, based on a live system state,
is also available in the Hyper-V Advisor Pack that is distributed with the
Server Performance Advisory tool described earlier in this guide.
Terminology
This section summarizes key terminology specific to virtual
machine technology that is used throughout this performance tuning guide:
Child partition
Any virtual machine that is created by the root partition.
emulated device
A virtualized device that mimics an actual physical hardware device so that guests can use the typical drivers for that hardware device.
device virtualization
A mechanism that lets a hardware resource be abstracted and shared
among multiple consumers.
Guest
Software that is running in a partition. It can be a full-featured operating system or a small, special-purpose kernel. The hypervisor is “guest-agnostic.”
Enlightenment
An optimization to a guest operating system to make it aware of virtual
machine environments and tune its behavior for virtual machines.
Hypervisor
A layer of software that sits above the hardware and below one or
more operating systems. Its initial job is to provide diverse execution
environments called partitions. Each partition has its own set of hardware
resources (central processing unit or CPU, memory, and devices). The hypervisor
is responsible for controls and arbitrates access to the underlying hardware.
Logical processor
A processing unit that handles one thread of execution (instruction
stream). There can be one or more cores per processor socket and one or more logical processors per core.
passthrough disk access
A representation of an entire physical disk as a virtual disk
within the guest. The data and commands are “passed through” to the physical
disk (through the root partition’s native storage stack) with no intervening
processing by the virtual stack.
Root partition
A partition that is created first and owns all the resources that
the hypervisor does not, including most devices and system memory. It hosts the
virtualization stack and creates and manages the child
Virtual machine
A virtual computer that was created by software emulation and has the same characteristics as a real computer.
Partitions.
Hyper-V-specific device
A virtualized device with no physical hardware analog, so guests may
need a driver (virtualization service client) to that Hyper-V-specific device.
The driver can use virtual machine bus (VMBus) to communicate with the
virtualized device software in the root partition.
Virtual processor
A virtual abstraction of a processor that is scheduled to run on a
logical processor. A virtual machine can have one or more virtual processors.
Virtualization service provider
A provider exposed bythe virtualization stack in the root partition that provides resources or services such as I/O to a child partition.
Virtualization service client
A software module that a guest loads to consume a resource or
service. For I/O devices, the virtualization service client can be a device
driver that the operating system kernel loads.
Virtualization stack
A collection of software components in the root partition that work
together to support virtual machines. The virtualization stack works with and
sits above the hypervisor. It also provides management capabilities.
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