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The ZDnet posting Review: Microsoft’s Hyper-V puts VMWare and Linux on notice is an early beta hands-on report.

The author, Jason Perlow, gives a summary of contemporary virtualization technologies:

Hyper-V, formerly known as “Viridian”, greatly differs from the virtualization product from Microsoft currently marketed as Microsoft Virtual Server in that it uses a hypervisor to provide hardware abstraction services to the OS environment and do resource allocation and partitioning. This differs from products such as Microsoft Virtual Server, VMWare Server and VMWare Workstation, Parallels, Linux KVM, and the recently Sun-acquired Virtualbox from Innotek use a technique known as host-based virtualization in which a host operating system such as Windows or Linux runs a subprocess provided by its native kernel called a Virtual Machine Monitor (VMM) to provide virtualization services such as a virtual CPU, memory and devices to a virtual machine. A hypervisor, on the other hand, is a thin abstraction layer which boots on the native hardware that performs some of the functions of an OS kernel, but abstracts much of what is needed to run multiple operating systems with their applications on top of it.

The advantages of hypervisor-based virtualization is that it tends to be faster and more enterprise scalable. The disadvantages are that hypervisors tend to be heavily hardware dependent and usually require hardware acceleration, such as Intel’s “VT” or AMD’s “Pacifica” extensions present in the latest Xeon and Opteron chips, such as it is with Hyper-V and Xen-based solutions, and require modified OS kernels and special paravirtualized device drivers to be run in the VM environment to facilitate enhanced I/O and networking performance.

VMWare’s ESX differs from Hyper-V and Xen in that it currently uses pure software based virtualization, so it doesn’t need the VT or Pacifica extensions. However, it has a much tighter environment as to what kind of hardware it can run on – the hypervisor has a limited device driver compatibility list and VMWare keeps its ESX hypervisor source code very close to the vest, so development goes at a much slower pace – SATA disk drives, which are now commonplace on commodity x86 server machines, are not currently supported in VMWare ESX 3. ESX Server also requires a special networked clustered file system known as VMFS to store the virtual machine images, and you have to dedicate a SAN-based LUN to it. Hyper-V, on the other hand, will run on any modern system that can run 64-bit Windows 2008, stores all its virtual machines on regular directories in NTFS, and provides third-party and built-in driver support by using what is referred to a “Parent” OS as a pass-thru mechanism. In Xen parlance, this is also referred to as “Domain 0”, where device and file system support is provided by the Linux kernel (or in the case of Sun xVM, Solaris) and Linux file systems such as ext3 and ReiserFS.

Check out Contemporary Virtual Technology for a more detailed comparison of the technologies.

My money is on VMware’s binary translation technology for a couple of reasons. It is further evolved then the contenders, and has virtual management tools making a living in the trenches of heavy-hitting businesses.

I think the biggest winning difference is VMware supports running most any x86 operating system straight out of the box. No munging required.

Here’s hoping competition pushes VMware to make its product line longer, lower, wider, faster, and cheaper.

…John

This entry was posted on Friday, February 15th, 2008 at 9:44 am and is filed under Technology, Virtual. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.