Support Policies and Recommendations for Exchange Servers in Hardware Virtualization Environments

Microsoft has published an interesting article about their official support for installing Exchange on Hyper-VVirtual Server 2005 virtual machines.

To make a long story short, here are the support policies for both Exchange 2007 and Exchange 2003:

Support Policy and Recommendations for Exchange Server 2007

Microsoft supports Exchange Server 2007 in production on hardware virtualization software only when all the following conditions are true:

• The hardware virtualization software is Windows Server 2008 with Hyper-V technology, Microsoft Hyper-V Server, or any third-party hypervisor that has been validated under the Windows Server Virtualization Validation Program.
• The Exchange Server guest virtual machine:
  • Is running Microsoft Exchange Server 2007 with Service Pack 1 (SP1) or later.
  • Is deployed on the Windows Server 2008 operating system.
  • Does not have the Unified Messaging server role installed. All Exchange 2007 server roles, except for the Unified Messaging role, are supported in a virtualization environment.
• The storage used by the Exchange Server guest machine can be virtual storage of a fixed size (for example, fixed virtual hard drives (VHDs) in a Hyper-V environment), SCSI pass-through storage, or Internet SCSI (iSCSI) storage. Pass-through storage is storage that is configured at the host level and dedicated to one guest machine.Note:

  In a Hyper-V environment, each fixed VHD must be less than 2,040 gigabytes (GB). For supported third-party hypervisors, check with the manufacturer to see if any disk size limitations exist.

  • Virtual disks that dynamically expand are not supported by Exchange.
  • Virtual disks that use differencing or delta mechanisms (such as Hyper-V’s differencing VHDs or snapshots) are not supported.
• No other server-based applications, other than management software (for example, antivirus software, backup software, virtual machine management software, etc.) can be deployed on the physical root machine. The root machine should be dedicated to running guest virtual machines.
• Microsoft does not support combining Exchange clustering solutions (namely, cluster continuous replication (CCR) and single copy clusters (SCC)) with hypervisor-based availability or migration solutions (for example, Hyper-V’s quick migration). Both CCR and SCC are supported in hardware virtualization environments provided that the virtualization environment does not employ clustered virtualization servers.
• Some hypervisors include features for taking snapshots of virtual machines. Virtual machine snapshots capture the state of a virtual machine while it is running. This feature enables you to take multiple snapshots of a virtual machine and then revert the virtual machine to any of the previous states by applying a snapshot to the virtual machine. However, virtual machine snapshots are not application-aware, and using them can have unintended and unexpected consequences for a server application that maintains state data, such as Exchange Server. As a result, making virtual machine snapshots of an Exchange guest virtual machine is not supported.
• Many hardware virtualization products allow you to specify the number of virtual processors that should be allocated to each guest virtual machine. The virtual processors located in the guest virtual machine share a fixed number of logical processors in the physical system. Exchange supports a virtual processor-to-logical processor ratio no greater than 2:1. For example, a dual processor system using quad core processors contains a total of 8 logical processors in the host system. On a system with this configuration, do not allocate more than a total of 16 virtual processors to all guest virtual machines combined.

Support Policy and Recommendations for Exchange Server 2003

Microsoft supports Exchange Server 2003 in production on hardware virtualization software (virtual machines) only when all the following conditions are true:

• The hardware virtualization software is Microsoft Virtual Server 2005 R2 or any later version of Microsoft Virtual Server.
• The version of Exchange Server that is running on the virtual machine is Microsoft Exchange Server 2003 with Service Pack 2 (SP2) or later.
• The Microsoft Virtual Server 2005 R2 Virtual Machine Additions are installed on the guest operating system.
• Exchange Server 2003 is configured as a stand-alone server and not as part of a Windows failover cluster.
• The SCSI driver that is installed on the guest operating system is the Microsoft Virtual Machine PCI SCSI Controller driver.
• The virtual hard disk Undo feature is not enabled for the Exchange virtual machine.Note:

  When a Microsoft Virtual Server SCSI adaptor is added to a virtual machine after the Virtual Machine Additions have been installed, the guest operating system detects and installs a generic Adaptec SCSI driver. In this case, the Virtual Machine Additions must be removed and then reinstalled for the correct SCSI driver to be installed on the guest operating system.

Rest of the recommendations are at Microsoft website.