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.
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
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.