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on January 28 2009, 10:36 PM
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MS Exchange Team:
With the release of Microsoft Windows Server 2008 with Hyper-V and Microsoft Hyper-V Server 2008, a virtualized Exchange 2007 SP1 server is no longer restricted to the realm of the lab; it can be deployed in a production environment and receive full support from Microsoft. This past August, we published our support policies and recommendations for virtualizing Exchange, but many people have asked us to go beyond that guidance and weigh-in on the more philosophical question: is virtualization is a good idea when it comes to Exchange?
Due to the performance and business requirements of Exchange, most deployments would benefit from deployment on physical servers. However, there are some scenarios in which a virtualized Exchange 2007 infrastructure may allow you to realize real benefits in terms of space, power, and deployment flexibility. Presented here are sample scenarios in which virtualization may make sense, as well as checklists to help you evaluate whether the current load on your infrastructure makes it a good candidate for virtualization.
Scenarios
Small Office with High Availability
Some organizations are small but they still require enterprise-class availability. For example, consider Contoso Ltd., a fictitious company that regards email as a critical service and has several small branch office site(s) consisting of 250 users. Contoso wants to keep their e-mail environment on-premises for legal reasons and they want to have a fully redundant email system. Contoso's users have average user profiles and the mailboxes are sized at 2 GB.
Before Hyper-V was introduced, to get full redundancy for all Exchange server roles, Contoso would have to deploy 7 physical servers: 2 servers for AD and DNS, 1 server for file and print, 2 servers running CAS and Hub, and 2 servers running the Mailbox role in a CCR environment. The servers are assumed to have 2 quad core processors and the amount of RAM is based on the installed roles. Each CCR node would have 4 GB of RAM, and each of the other servers would have the minimum 2 GB of RAM to support the users and traffic pattern. With user profiles this size, the average load would be 35-45% of CPU on a server that has eight cores.
Flip the page to today and Contoso can give the same level of redundancy and availability with only 3 servers by using virtualization. Each physical server would run each of the roles as a Hyper-V guest. In this scenario, 3 physical servers with 2 quad core processors and 16 GB of RAM would have sufficient capacity to serve Contoso's users. Along with RAM and processors, the servers need to have multiple NICs and redundant paths for storage. Since Contoso still has the same number of Exchange servers to manage, they have not benefitted much from the O&M perspective, but think about the space, power, and HVAC impact. Each of the virtual servers would be configured with 2 virtual CPUs.
The following diagram illustrates the scenario. Note that the Hub Transport Exchange 2007 Server serving as the File Share Witness (FSW) is on a separate Hyper-V host from the CCR Mailbox Nodes to eliminate any single point of failure in the clustering solution and to provide true clustering capability.
Figure 1 - Possible Small Branch Office Design for Exchange 2007 SP1 on Hyper-V
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