The hypervisor war rages on: A look at the new Hyper-V R2

Microsoft may have to exhibit in a 10-by-10 space at competitor VMware's VMworld show, but will that really contain the growing Hyper-V?

The famous words "nobody puts baby in a corner" come to mind. Yes, it is true that this year the two major competitors to EMC's VMWare subsidiary are each being relegated to a 10-by-10 booth space at this week's VMworld show put on by VMware. If you have ever exhibited a product before, you know that is barely enough room for a small company, much less a Microsoft or Citrix. Put simply, it's their show, it's not an industry show, and they set the rules. The rules say "complementary products" are allowed, but apparently not competitive products. Microsoft and Citrix will not even be able to demo their products at their booths.

But will that shoehorned space and the restrictive presentation rules dampen the momentum toward Microsoft's Hyper-V? It isn't likely, although virtualization front-runner VMware's putting its competitors into tiny booths and restricting what they can show does seem a bit childish.

[ Read the InfoWorld Test Center reviews of Microsoft Windows Server 2008, Hyper-V and System Center Virtual Machine Manager, VMware Infrastructure 3 with ESX Server 3.5 and VirtualCenter 2.5, and Citrix XenServer and XenDesktop. ]

In all fairness, VMware is not the only company that has been childish at VMworld. Last year, even though Microsoft has been a gold sponsor at previous VMWare events, its staff handed out poker chips at the Microsoft booth printed with negative comments about VMWare. Childish behavior apparently begets childish behavior.

Microsoft isn't taking this year's restrictions lying down, though. Its people are at the show talking to customers, and the company put out a press release sure to displease VMware by showing how much money companies save by moving from VMWare to Microsoft virtualization.

Beyond the show antics: A look at the new Hyper-V R2

So what is this war all about? It's about hypervisors, the software that lets an OS run on another OS (called a Type 2 hypervisor) or directly on a bare-metal server (a Type 1 hypervisor) even though the OS may or may not be designed to run on that hardware directly. VMWare Workstation, Parallels Desktop, and Microsoft's Virtual PC are Type 2 hypervisors. But Type 1 hypervisors are where the action is: letting multiple OSes run on the same server hardware to achieve the flexibility and scalability that gets IT so excited about virtualization technology in the first place. VMware's ESX is the leading Type 1 hypervisor, followed by Citrix's XenServer and Microsoft's more recent Hyper-V.

Today, Microsoft is virtualization's David to VMware's Goliath, and the two hypervisors take different approaches that anyone looking at deploying virtualization should understand. In this column, I'll focus on Hyper-V; I'll focus on ESX in a later column.

Hyper-V is a microkernelized hypervisor, while ESX is a monolithic one. That means ESX includes all of its device drivers within the hypervisor, making it a bit bigger (30MB or more); any new devices have to be integrated into that hypervisor as well. By contrast, Hyper-V keeps the hypervisor smaller (less than 1MB) by using an administrative parent OS that has all of the drivers. Strictly speaking, a smaller hypervisor means better performance, although benchmarking has shown that the performance between these two products is fairly close.

Hyper-V is part of some editions of Windows Server 2008, while ESX is an individual product; if you're buying one of the Hyper-V-equipped Windows Server 2008 editions anyhow, Hyper-V is essentially free. And this week, turning up the heat on VMware, Microsoft made available as a free download its stand-alone Microsoft Hyper-V Server 2008 R2 version.

You might be thinking, "If Hyper-V will save me money, and performance isn't necessarily the biggest factor here, why wouldn't I move to Hyper-V?" First off, VMWare has been in the server market since 2001 whereas Hyper-V is about a year old (and the latest R2 stand-alone version just a few days old).

Hyper-V R1 does have limitations, the biggest of which is a lack of support for Live Migration, which is the ability to move a virtual machine from one physical host over to another while powered up. The server can be moved over and running the entire time. This feature can help to avoid a crash because, if you know a problem is brewing, you can move your servers over before the crash. It can also help with load balancing by moving servers off to systems that aren't using as many resources. (Note: Live migration isn't the same as a high-availability tool, so it won't do failover for you in case of a crash.) If you do the live migration correctly, the users should not even notice.

Hyper-V R1 does have a feature called Quick Migration that lets you move VMs, but you have to suspend the state of the VM, and this suspension (although quick) is noticeable to the users. For many IT shops, the lack of live migration in Hyper-V was a deal-breaker. So it is no surprise that Microsoft has released Hyper-V R2 into Windows Server 2008 R2 and the stand-alone Hyper-V R2 just this week, in time for VMWorld. Here's a table comparing Hyper-V R1 and R2, based on information from Microsoft's Virtualization Product Group:

Comparing Microsoft Hyper-V Server R1 to R2
FeatureMicrosoft Hyper-V Server 2008 R1Microsoft Hyper-V Server 2008 R2
Physical processor supportUp to 4 processorsUp to 8 processors
Logical processor supportUp to 16Up to 64
Physical memory supportUp to 32GBUp to 1TB
Live migrationNoYes
High availablilityNoYes
Management optionsHyper-V MMC, Windows Server 2008, System Center Virtual Machine Manager 2008 R2Remote Server Administration Tool (free), Windows Server 2008 R2 System Center Virtual Machine Manager 2008 R2

You should note the following other features in Hyper-V R2:

  • Support for running up to 384 virtual machines with up to 512 virtual processors
  • Processor compatibility mode for live migration across different processors from the same vendor
  • Hot add/remove of virtual storage
  • Networking enhancements: VMQ, Chimney, and support for jumbo frames
  • Simplified management using sconfig
  • Boot from flash

Stay tuned! Next week I will interview a vExpert about the VMWare product lineup. Let's see what a 10-year head start can accomplish!

Learn more about Hyper-V from J. Peter Bruzzese at this year's WinConnections in Las Vegas with his session "Hyper-V: Down and Dirty." Follow J. Peter Bruzzese on Twitter at

Copyright © 2009 IDG Communications, Inc.

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