To leap beyond its competition in the area of server
virtualization, Microsoft had to make some significant changes to the
operating system that hosted its next-generation virtual server
technology. With the original Windows 2008 in development, Microsoft
took the opportunity to add in a core technology to Windows 2008 (and
extended it in Windows 2008 R2) that provided the basis of Microsoft’s
future dominance in server virtualization. The core technology is called
hypervisor, which effectively is a layer within the host operating
system that provides better support for guest operating systems.
Microsoft calls their hypervisor-based technology Hyper-V.
Prior to the inclusion of
Hyper-V in Windows 2008 and Windows 2008 R2, the Virtual Server
application sat on top of the host operating system and effectively
required all guest operating systems to share system resources, such as
network communications, video-processing capabilities, memory
allocation, and system resources. In the event that the host operating
system has a system failure of something like the host network adapter
driver, all guest sessions fail to communicate on the network. This
monolithic approach is similar to how most server virtualization
technologies operate.
Technologies
like VMware ESX as well as Hyper-V leverage a hypervisor-based
technology that allows the guest operating systems to effectively bypass
the host operating system and communicate directly with system
resources. In some instances, the hypervisor will manage shared guest
session resources, and in other cases will pass guest session requests
directly to the hardware layer of the system. By providing better
independence of systems communications, the hypervisor-supported
environment provides organizations better scalability, better
performance, and, ultimately, better reliability of the core virtual
host environment.
Hyper-V is available in Windows
Server 2008 R2 Standard, Enterprise, and Datacenter Editions. Each of
these SKUs are available with and without Hyper-V.
Note
Hyper-V in Windows
Server 2008 R2 is only supported on x64-bit systems that have
hardware-assisted virtualization support. CPUs must support Intel VT or
AMD-V option and Data Execution Protection (DEP). Also, these features
must be enabled in the computer BIOS. Fortunately, almost all new
servers purchased since late 2006 include these capabilities.
What’s New in Windows
Server 2008 R2 Hyper-V
There are many long-awaited
features and technologies built in to Hyper-V that provide Microsoft the
ability to compete with other server virtualization products on the
market. Some of the key additions to Hyper-V include the following:
Live Migration— Live Migration is the number-one
most-requested feature by customers. Live Migration enables
administrators to migrate highly available Hyper-V guests between
clustered hosts with nearly zero downtime.
Support
for up to eight physical processors—
Windows 2008 Server R2 virtualization provides the capability to have
up to eight physical processors—twice the number of physical processors
supported by Hyper-V V1 in Windows Server 2008. Note that this refers to
physical sockets, not cores.
Support for up to 64
logical cores per guest session—
Windows Server 2008 R2 virtualization provides the capability to have up
to 64 logical processors (cores) allocated to a single guest
session—four times better than in Windows Server 2008.
Support
for greater physical host memory—
Windows Server 2008 R2 virtualization supports up to 1TB physical memory
allocation per host—a huge increase from the 32GB supported in Windows
Server 2008.
Support for greater virtual guest memory— Virtual guests can now access up to 64GB per VM.
This is a huge scalability improvement from Windows Server 2008, where
VMs were limited to 32GB total RAM per host.
Note
Although
Hyper-V provides the capability to host guest operating systems for
Windows servers, client systems, and non-Windows systems, many of the
tools enterprises use in virtual server environments require the
addition of the System Center Virtual Machine Manager (VMM) tool.
VMM provides a more
centralized view and administration of multiple virtual guest sessions,
the tools to do physical-to-virtual image creation, virtual-to-virtual
image copying, and load balancing of virtual images across VMM servers.
VMM adds the administrative tools that take the basic virtual server
sessions, and provides administrators the ability to better manage the
guest sessions.
Microsoft Hyper-V
Server as a Role in Windows Server 2008 R2
Hyper-V is enabled as a server
role just as Windows Server 2008 R2 Remote Desktop Services, DNS
Server, or Active Directory Domain Services are added to the server.
