Virtualizing Exchange Server on Hyper-V versus VMware

Some experts turn the virtualization debate between Microsoft Hyper-V versus VMware vSphere into an emotional, almost religious crusade. However, the discussion of which platform is best for an organization can be boiled down to a logical list of pros and cons.

No matter which platform you choose, virtualizing Exchange offers hardware independence and improved disaster recovery options. For this mission-critical application, being able to swap out a server on lease or quickly fail over to a compatible server when a disaster occurs makes virtualizing Exchange on any platform a wise decision.

Before directly comparing the pros and cons of Microsoft Hyper-V versus VMware vSphere, let's consider a few points:

  1. You are going to virtualize Exchange 2007 or Exchange 2010 and move the server from physical to virtual hardware.
  2. You plan to run virtualized Exchange on Windows Server 2008 SP2 or Windows Server 2008 R2.
  3. You will virtualize all Exchange server roles, except for unified messaging.
  4. A dedicated server will run only Exchange and support either virtualization Hyper-V or vSphere.
  5. You have no bias toward either Microsoft Hyper-V or VMware vSphere. While this point may not seem that important, every organization has some pre-disposition about Microsoft versus VMware, especially if it already has virtualized applications from one vendor. For most companies, it makes sense to virtualize Exchange on the same virtualization platform as other enterprise servers.

Exchange Server virtualization: Hyper-V or vSphere?
There are a few questions to ask when weighing the pros and cons of virtualizing Exchange Server on either Hyper-V and vSphere. When trying to decide with product is best for your organization, consider these points:

Cost -- What costs are associated with each virtualization platform?

Microsoft Hyper-V -- You have two choices for virtualizing Exchange Server on Microsoft Hyper-V: Hyper-V Server 2008 R2, which is free, or Windows Server 2008 R2, which costs $1,029 with System Center Virtual Machine Manager (SCVMM) Workgroup, which costs $505.

Windows Server’s virtual instance license states that you must use the OS on one virtual machine (VM) with the Standard edition and four VMs with Enterprise edition. If you already have a Windows Server 2008 R2 license for Exchange, you can use that as the Hyper-V host license in your Exchange guest VM. However, that would be the only VM you could run on that server without having to purchase another license.

VMware vSphere -- There are also two options for virtualizing Exchange Server on VMware vSphere: use ESXi, VMware’s free hypervisor or purchase vSphere Essentials, which includes vCenter Essentials, for $611.

Exchange Server is an enterprise application, so you should research a platform with robust features and support. Therefore, you may want to consider higher-end editions of Hyper-V and vSphere.

A Windows Server Enterprise 2008 R2 license lets you run four Windows VMs at no additional cost, but lacks the advanced features that vSphere offers. vSphere Enterprise Plus doesn't include any Windows guest OS licenses, though it does include several advanced features, such as hot-add virtual CPU (vCPU) and RAM, 8-way virtual symmetric multiprocessing (vSMP), storage and network I/O control, as well as several advanced-memory management techniques.

  • Check out these additional resources for specific, feature-by-feature comparisons of VMware vSphere and Microsoft Hyper-V:

    Windows Enterprise 2008 R2 costs $3,999 and vSphere Enterprise Plus costs $3,495. When you include the features and options in each package, the pricing is very similar.

  • Feature set -- Which virtualization platform offers the most, and best, features?
  • Hyper-V is missing a few key features. It lacks memory optimization capabilities such as transparent page sharing, memory compression and memory ballooning. However, when run on Windows Server 2008 R2 SP1, Hyper-V has dynamic memory that competes with VMware’s memory over commitment -- although the two work very differently.

    Additionally, Microsoft will not fully support a virtualized Exchange server running on Hyper-V if you want to:

    • Use snapshots;
    • Use VMotion or Quick or Live Migration, as VMotion prevents you from using VMware’s DRS clustering.
    • Use dynamic disks or thin-provisioned disks.
    • Have any other software installed on the host server except for backup, antivirus and virtualization management software.
    • Exceed a 2:1 virtual-to-physical (V2P) processor ratio.

    In my opinion, these limitations prevent organizations from benefitting from some of the best virtualization features -- snapshots, VMotion and Quick or Live Migration.

    vSphere offers numerous advanced features that you may want to take advantage of for other VMs running on the same server, like distributed resource scheduler (DRS), distributed power management (DPM), VMotion, Storage VMotion and VMware high availability (HA).

    You may not be able to use all of VMware's features on your Exchange VM; however, you generally can use them for different VMs running on the same server. In doing this, you'll be able to place more VMs on a single vSphere server. Don’t overdo this, though, as VM sprawl can negatively affect performance.

  • Note: The cost and features comparisons above are not full comparisons of these two platforms. For more cost and feature comparisons, I recommend the following resources:
  • vSphere vs. Hyper-V Comparison
    Choosing vSphere vs. Hyper-V vs. XenServer
    How to run Exchange 2010 on Hyper-V R2
  • Resources and educational options -- How much information and support is readily available online about each platform? When you need help with your virtualized Exchange infrastructure, which platform is there more information on?

    In my opinion, the VMware community offers more educational options, innumerable blog posts, certification options and additional guides. There also are more conferences and resources available that focus on VMware.

  • Third-party support and tools -- How many third-party tools are on the market for each virtualization platform? How many new tools are released, on average, in a month or a year? While there are quite a few free and paid tools out there for Hyper- V, it seems that there are more options for companies working with vSphere.
  • Scope of product line -- It’s important to consider product maturity, how much each vendor has invested in its virtualization platform and its plans for future growth.

    Because Exchange Server and Hyper-V are both Microsoft products, you can use a single product suite -- System Center -- to manage them both (in one way or another). Although the suite has fewer features than VMware’s tools, there may be benefits to having your management layer all from the same vendor.

VMware offers more than 20 different virtualization pieces that fit into its overall vSphere product line. This is important because you may want to expand your company’s virtual infrastructure and will need more than what is offered natively.


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