Information Technology Reference
In-Depth Information
Real World Scenario: VMware vSphere Compared to Hyper-V and
XenServer
It's not really possible to compare some virtualization solutions to other virtualization solutions
because they are fundamentally diff erent in approach and purpose. Such is the case with VMware
ESXi and some of the other virtualization solutions on the market.
To make accurate comparisons between vSphere and other virtualization solutions, you must include only
Type 1 (“bare-metal”) virtualization solutions. h is would include ESXi, of course, and Microsoft Hyper-V
and Citrix XenServer. It would not include products such as VMware Server and Microsoft Virtual Server,
both of which are Type 2 (“hosted”) virtualization products. Even within the Type 1 hypervisors, there
are architectural diff erences that make direct comparisons di cult.
For example, both Microsoft Hyper-V and Citrix XenServer route all the VM I/O through the
“parent partition” or “dom0.” h is typically provides greater hardware compatibility with a wider
range of products. In the case of Hyper-V, for example, as soon as Windows Server 2012—the
general-purpose operating system running in the parent partition—supports a particular type of
hardware, Hyper-V supports it also. Hyper-V “piggybacks” on Windows's hardware drivers and the
I/O stack. h e same can be said for XenServer, although its “dom0” runs Linux and not Windows.
VMware ESXi, on the other hand, handles I/O within the hypervisor itself. h is typically provides
greater throughput and lower overhead at the expense of slightly more limited hardware compat-
ibility. In order to add more hardware support or updated drivers, the hypervisor must be updated
because the I/O stack and device drivers are in the hypervisor.
h is architectural diff erence is fundamental. Nowhere is this architectural diff erence more greatly
demonstrated than in ESXi, which has a small footprint yet provides a full-featured virtualization
solution. Both Citrix XenServer and Microsoft Hyper-V require a full installation of a general-
purpose operating system (Windows Server 2012 for Hyper-V, Linux for XenServer) in the parent
partition/dom0 in order to operate.
In the end, each of the virtualization products has its own set of advantages and disadvantages, and
large organizations may end up using multiple products. For example, VMware vSphere might be
best suited in the large corporate datacenter, while Microsoft Hyper-V or Citrix XenServer might
be acceptable for test, development, or branch-o ce deployment. Organizations that don't require
VMware vSphere's advanced features like vSphere DRS, vSphere FT, or Storage vMotion may also
fi nd that Microsoft Hyper-V or Citrix XenServer is a better fi t for their needs.
As you can see, VMware vSphere offers some pretty powerful features that will change the
way you view the resources in your datacenter. vSphere also has a wide range of features and
functionality. Some of these features, though, might not be applicable to all organizations, which
is why VMware has crafted a l exible licensing scheme for organizations of all sizes.
Licensing VMware vSphere
With the introduction of VMware vSphere 4, VMware introduced new licensing tiers and bun-
dles that were intended to provide a good i t for every market segment. That arrangement con-
tinued with vSphere 5.0. However, with vSphere 5.1 (and continuing with vSphere 5.5), VMware
rei ned this licensing arrangement with the introduction of the vCloud Suite—a bundling
