V for Virtualization, XenServer vs Hyper-V vs VMware

The recent availability of Microsoft Hyper-V has generated an enormous amount of interest and inevitable questions for our sales engineers. If you have a project on plan this year and want to discuss it in person with one of our consultants then contact us. Meanwhile I'd like to take this opportunity to dispel some myths and inform a few truths about this triumvirate facing IT managers in 2009.

Firstly, although there are many more than 3 companies offering similar "whole system" x86 server virtualization, there are only 3 that are significant at this point, expect the rest to be acquired or fold as they fail to achieve critical mass. This leaves us with:

• VMware, the market leader, indeed the market creator.

• Citrix XenServer, commercial progeny of the open source Xen project.

• Hyper-V, Microsoft's 2nd take, now they decided it is a good thing after all.

VMware is by far the most mature, as one would expect, having several years head start in the tough world of large enterprise data centers. To borrow a phrase from one of our own articles any fragile bits have long since broken off. VMware has its sales channels, OEM technology partners, and end user support network humming along nicely. VMware was also the first to introduce high availability and enterprise management features, and through it's large installed-base has the broadest support for guest operating systems (but all 3 vendors still support the majority of OS found in a typical business). For a long time VMware was the only game in town and priced the product accordingly, recruiting a large number of value added resellers, consultancy firms, and integrators to their flag. However being the first-in does have its disadvantages, its very expensive to break a new market and this pushed up the price of the product to the end user. VMware was founded in 1997 and although the product has been regularly updated there are still vestiges of its 90's heritage, particularly around the relative cost (then versus now) of CPU, RAM, and the need for a separate management server to hold the cluster database. 360is consultants have been deploying VMware in one form or another since the late 90's and are experts in its application to datacenters.

Xen took a fresh look at x86 virtualization in 2002/3, starting out as a research project at Cambridge University, spawning a commercial entity (XenSource) acquired by Citrix in 2007. The approach taken by Xen, and used in the XenServer product is to have an extremely thin virtualization layer between physical hardware and guest OS, and to do the minimum required to allow those guests to run safely together on a system. This approach was made possible by advances in CPU design by Intel and AMD around the time of Xen's formation. Indeed, CPU vendors are still among Xen's largest backers. XenServer has a number of enterprise features like High Availability, Live Migration, and integration with enterprise storage vendors, while still lacking some depth compared to VMware. Our experience is that most XenServer installations are bought on a combination of price and performance. XenServer costs between one half and one third the price of a VMware setup, and this is before staffing is considered. Performance remains a differentiator particularly where extreme consolidation is desired, or where the applications are particularly demanding. 360is staff have been working with XenServer commercially since 2007 and are the UK's most experienced partner.

Hyper-V is free. It is Microsoft's 2nd crack at virtualization after MS Virtual Server which was a disappointment. Hyper-V is a ground-up rewrite and like VMware ESX and Xenserver is a Type-1 or "native bare metal" hypervisor. As such it is loaded onto the physical hardware of the server and all guests run in a layer above it. Early on in the products development, Microsoft tapped XenSource for expertise on running Linux guests and managing scheduling. Hyper-V currently lacks most of the enterprise features of either of the other 2 products, including lacking live migration/vmotion. That said, Hyper-V will become ubiquitous though its low price and wide distribution channel. Our initial testing has Microsoft's product in 3rd place behind XenServer and VMware for performance, particularly with memory-access-intensive workloads, but no-doubt this will be improved upon in future releases. We have yet to see a client using Hyper-V in production but we have many running it in test and development.

So what's an infrastructure manager or CIO to do? Is there such a thing as the right hypervisor? Or a wrong one? After all, you wouldn't want to have been the person who cabled up his building for token ring only to switch to ethernet 2 years later.

Of course we are talking about a false dichotomy, no matter what the vendors say.

Providers of the core hypervisor technology will continue to play a game of technical leapfrog with one another for at least a couple of years, while those with a management, enterprise framework, or suite will claim more strategic long-term positions around "liquid infrastructure" or something else suitably bendy. What is most important right now is that you have the right information processing architecture, not any one particular product within it. What am I talking about when I say this?

• Tiered, shared storage
• Network that scales at an acceptable cost
  
• A capacity planning model correct for your particular setup
  
• Accurate and appropriate information on performance

...where failure (hardware, software, or the human sort) is accepted and planned for, after all, there are no certainties in life besides death, taxes, and the failure at some point of an IT system. As someone once said, "There are only two kinds of storage devices - those that have failed, and those that are about to fail".

Ultimately, virtualization is about making more efficient use of hardware and of the man-hours spent managing it, mostly through resource sharing and the enablement of faster provisioning and tear-down (or migration) of new services or workloads. Like most advances in technology, the real barrier to benefits are more likely to be your ability to accept virtualization into the core of your operation and to adapt your behavior and ways of working around accordingly.

360is helps our clients adapt IT operations to a fully virtualized infrastructure no matter which of the 3 dominant hypervisors best suits their purpose. Remember, a good IT infrastructure impresses, a great one is invisible.