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3 Benefits of Running Exchange Server in a Virtualized Environment Guest post by: Brien M. Posey
One of the big decisions that administrators must make when preparing to deploy Exchange Server is whether to run Exchange on physical hardware, virtual hardware, or a mixture of the two. Prior to the release of Exchange Server 2010 most organizations chose to run Exchange on physical hardware. Earlier versions of Exchange mailbox servers were often simply too I/O intensive for virtual environments. Furthermore, it took a while for Microsoft’s Exchange Server support policy to catch up with the virtualization trend. Today these issues are not the stumbling blocks that they once were. Exchange Server 2010 and 2013 are far less I/O intensive than their predecessors. Likewise, Exchange Server is fully supported in virtual environments. Of course administrators must still answer the question of whether it is better to run Exchange Server on physical or on virtual hardware. Typically there are far greater advantages to running Exchange Server in a virtual environment than running it in a physical environment. Virtual environments can help to expedite Exchange Server deployment, and they often make better use of hardware resources, while also offering some advanced protection options. Improved Deployment At first the idea that deploying Exchange Server in a virtual environment is somehow easier or more efficient might seem a little strange. After all, the Exchange Server setup program works in exactly the same way whether Exchange is being deployed on a physical or a virtual server. However, virtualized environments provide some deployment options that simply do not exist in physical environments. Virtual environments make it quick and easy to deploy additional Exchange Servers. This is important for any organization that needs to quickly scale they are Exchange organization to meet evolving business needs. Virtual environments allow administrators to build templates that can be used to quickly deploy new servers in a uniform way. Depending upon the virtualization platform that is being used, it is sometimes even possible to set up a self-service portal that allows authorized users to deploy new Exchange Servers with only a few mouse clicks. Because the servers are based on preconfigured templates, they will already be configured according to the corporate security policy. Hardware Resource Allocation Another advantage that virtualized environments offer over physical environments is them virtual environments typically make more efficient use of server hardware. In virtual environments, multiple virtualized workloads share a finite pool of physical hardware resources. As such, virtualization administrators have gotten into the habit of using the available hardware resources efficiently and making every resource count. Of course it isn’t just these habits that lead to more efficient resource usage. Virtualized environments contain mechanisms that help to ensure that virtual machines receive exactly the hardware resources that are necessary, but without wasting resources in the process. Perhaps the best example of this is dynamic memory. The various hypervisor vendors each implement dynamic memory in their own way. As a general rule however, each virtual machine is assigned a certain amount of memory at startup. The administrator also assigns maximum and minimum memory limits to the virtual machines. This allows the virtual machines to claim the memory that they need, but without consuming an excessive percentage of the servers overall physical memory. When memory is no longer actively needed by the virtual machine, that memory is released so that it becomes available to other virtual machines that are running on the server. Although mechanisms such as dynamic memory can certainly help a virtual machine to make the most efficient use possible of physical hardware resources, resource usage can be thought of in another way as well. When Exchange Server is deployed onto physical hardware, all of the servers resources are dedicated to running the operating system and Exchange Server. While this may initially sound desirable, there are problems with it when you consider hardware allocation from a financial standpoint. In a physical server environment, the hardware must be purchased up front. The problem with this is that administrators can simply purchase the resources that are needed by Exchange Server based on current usage. Workloads tend to increase over time, so administrators must typically purchase more memory, CPU cores, and faster disks than what are currently needed. These resources are essentially wasted until the day that the Exchange Server workload grows to the point that those resources are suddenly needed. In a virtual environment this is simply not the case. Whatever resources are not needed by a virtual machine can be put into a pool of physical resources that are accessible to other virtualized workloads. Protection Options One last reason why it is often more beneficial to operate Exchange Server in a virtual environment is because virtual environments provide certain protection options that are not natively available with Exchange Server. Perhaps the best example of this is failover clustering. Exchange Server offers failover clustering in the form of Database Availability Groups. The problem is that Database Availability Groups only protect the mailbox server role. Exchange administrators must look for creative ways to protect the remaining server roles against failure. One of the easiest ways to achieve this protection is to install Exchange Server onto virtual machines. The underlying hypervisor can be clustered in a way that allows virtual machines to fail over from one host to another if necessary. Such a failover can be performed regardless of the limits of the operating system or application software that might be running within individual virtual machines. In other words, virtualization allows you to receive the benefits of failover clustering for Exchange server roles that don’t normally support clustering. Conclusion As you can see, there are a number of benefits to running Exchange Server in a virtual environment. In almost every case, it is preferable to run Exchange Server on virtual hardware over physical hardware.  
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