Exchange Server Virtualization Support Policy Summary

Monday, August 25, 2008
Microsoft released their Microsoft Support Policies and Recommendations for Exchange Servers in Hardware Virtualization Environments document this month. I reviewed the support document and summarized the salient facts here.
Exchange 2007 Virtualization

Host Requirements:
  • A hypervisor virtualization solution that has been validated by the Windows Server Virtualization Validation Program
  • Adequate storage space to accommodate the host OS and components, paging file, management software and crash recovery (dump) files
  • Storage space must be allocated for Hyper-V temporary memory storage (BIN) files, equal to the amount of RAM allocated to each guest
Guest Requirements:
  • Exchange 2007 SP1 (or later) deployed on Windows Server 2008
  • Cannot have the Unified Messaging Role installed
  • The total maximum number of virtual processors cannot exceed the twice the number of physical cores.Typically 2 virtual processors are required for each Exchange server guest, but use this as a baseline
  • Large mailboxes (1GB and larger) require the use of Cluster Continuous Replication (CCR)
  • CCR nodes must be hosted on separate physical host servers to provide true redundancy and high availability
  • Mixing physical and virtual nodes is supported for CCR and SCC environments
  • Exchange supported backups must be run from the guest
  • Both legacy backups (using ESE streaming APIs) and Exchange-aware software-based VSS backups (Data Protection Manager) are supported
  • VSS backups of the an Exchange guest is supported if the guest uses only VHDs (not pass-through disks)
Guest Storage Requirements:
  • Supports fixed size VHDs, SCSI pass-through and iSCSI storage
  • Storage must be dedicated to one guest machine. In other words, a pass-through disk must be dedicated to one, and only one, guest.
  • Guest OS must use a minimum fixed-size VHD of 15GB plus the size of virtual RAM allocated to the guest
  • VHD limit is 2,040GB (nearly 2TB) in Hyper-V
  • Hub and Edge Transport servers require sufficient storage for message queues and log files
  • Mailbox servers require sufficient storage for databases and log files
  • iSCSI storage using an iSCSI initiator within the guest is supported. This offers greater portability, but decreased performance
Not Supported:
  • Dynamically expanding VHDs are not supported
  • Snapshots or differencing disks are not supported
  • Virtualization high availability solutions, such as Hyper-V Quick Migrations, are not supported. Only Exchange aware HA solutions (SCC, LCR, CCR and SCR) are supported.
  • VSS backups of the Exchange guest machine's pass-through disk from the host are not supported
  • Storage should be hosted on separate disk spindles from the guest's OS
  • Use SCSI pass-through storage to host transport and mailbox databases and transaction logs
  • When using iSCSI storage, configure the iSCSI Initiator on the host and present it as a pass-through disk to the guest
  • Use dedicated NICs with jumbo frames and not bound to a Virtual Network Switch, Gigabyte Ethernet, and isolated networks for iSCSI storage
Exchange 2003 Virtualization

Host Requirements:
  • The hardware virtualization software is Microsoft Virtual Server 2005 R2 or any later version of Microsoft Virtual Server
Guest Requirements:
  • Exchange Server 2003 SP2 (or later)
  • Microsoft Virtual Server 2005 R2 Virtual Machine Additions must be 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
  • Each guest must have only one CPU
Guest Storage Requirements:
  • The SCSI driver 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
  • Consider adding a dedicated virtual network adaptor for Exchange Server backups
  • Create separate fixed-size VHDs for Exchange Server databases and log files and store them on separate physical drives on the host
  • Exchange Server performance should be validated before production by using the Exchange Server 2003 Performance Tools
  • Make sure that the host server is sized correctly to handle the number of virtual machines that you plan to deploy
  • Use a storage solution that enables fast disk access
  • Antivirus programs should be configured to not scan VHD files