To Hyper-V or not to Hyper-V?

It’s here! Hyper-V.


Is Exchange 2007 a good candidate for virtualisation? Well only in certain situations and for certain roles and we’ll discuss this later.


Some applications can have major advantages from increased utilization of hardware, simplified and flexible deployment. A virtualized technology is not necessarily suited to every server workload or application, in fact some are a poor fit and hamper the business benefit if virtualized. Mission critical applications are often poor candidates for virtualization, the cost/efficiency can be outweighed by the risks.


Let’s have a look at how Hyper-V should be configured for Exchange 2007 SP1:


Root OS configuration

· Separate LUN’s / Arrays for root OS, Guest OS VHD’s and Hyper-V storage

· Snapshot creation and differencing disks for VM’s are not supported for production environments

· Oversubscribing CPU’s greater than 2:1 (Virtual processor / Physical core) is not supported for Exchange

· No Exchange (or other applications) running in the root OS


Guest OS Configuration

· Windows 2008 and Exchange 2007 SP1 only

· Fixed VHD’s for virtual OS

· Account for pagefile consumption in addition to OS requirements


Exchange Storage Configuration

· Exchange storage should be separate spindles from the guest OS VHD physical storage

· Exchange storage must be using a fixed VHD, SCSI pass-through or iSCSI

· FC/SCSI HBA’s must be configured to root OS and LUN’s presented to VM’s as passthrough or VHD

o Separate iSCSI Gigabit network recommended

o Dedicated NIC


High Availability

· There is an automatic switch over of application services which doesn’t affect the integrity of the application

· Hyper-V is a good fit for the branch office scenario when servers in the branch office cannot be consolidated to a central datacenter, this could be due to bandwidth or connectivity issues (Hyper-V enables 50% reduction of physical server count in branch scenarios when HA is required)



In some environments (such as branch offices) consolidating servers into Hyper-V provides many benefits. The servers which are good candidates for Hyper-V consolidation are Active Directory (AD) servers, Exchange 2007 SP1 Client Access Servers (CAS) and Exchange 2007 SP1 Hub Transport Servers (HT).

· Exchange 2007 SP1 Mailbox role –

o This server role is NOT a good candidate for virtualisation as it increases the overall risk for such a critical resource.

o Adds additional complexity to an already complex configuration.

o The mailbox role is a highly utilized role and has few resources available for sharing

o Requires additional network interfaces and complexity especially with storage e.g. iSCSI

Unsupported configuration

· Unified Messaging Server Role

· Hardware VSS/VDS

· VHD Disk > 2040GB


For more information on Hyper-V consolidation see Virtualization and Consolidation with Hyper-V and Identifying Server Candidates for Virtualization



Written by Daniel Kenyon-smith