Virtualizing Exchange has been a topic of great controversy ever since virtualization first came on the scene. In the early years of virtualization, it was recommended NOT to run Exchange in a virtual environment because of the limitations of the infant technology. Since then, virtualization has matured in a way that has removed many, if not all, of those limitations. Unfortunately, the recommendations of the past have remained as a worry in today’s discussions surrounding the partnership of virtualization and Exchange. The truth is Microsoft fully supports the virtualization of Microsoft Exchange today. As with any other environment, you must be sure that you configure your virtual platform to properly support Exchange, but there are no limitations within Microsoft’s Hyper-V technology that should cause any concern in your discussions to virtualize Exchange. There are some key items that Microsoft has called out that IS professionals should be aware of when designing their virtual Exchange environments.
- The software platform should be Windows Server 2008, or any thirdparty vendor virtualization platform that has been validated by Microsoft’s Windows Server Virtualization Validation Program. Located here: www.windowsservercatalog.com/svvp.aspx?svvppage¼svvp.htm, the Validation Program includes some of the most well-known vendors of both hardware and software. The site will help you to identify those who have been validated by Microsoft to provide platforms capable of running all flavors of the Microsoft Servers.
- If you are planning to virtualize your Exchange environment, you must use Exchange Server 2007 with Service Pack 1 or later. Earlier, Exchange versions are not fully supported on a virtual platform. The use of the Unified Messaging role is not supported if your Exchange server is running within a virtual platform. It is important to note that the base Exchange 2007 system requirements WITHOUT the use of virtualization is Windows 2003, but the use of this operating system as a host for Exchange 2007 is not supported in the virtualization world. We mention this because some may consider building Exchange 2007 in a nonvirtual environment with the plan to migrate the complete operating system into Hyper-V at a later date. If you plan to do this, you must build your environment using Windows 2008 or later.
- Exchange 2007 on a virtual platform supports all of the most common forms of storage. These include virtual hard drives (VHD), SCSI, and iSCSI storage. If you plan to use SCSI or iSCSI, you must configure it to be presented as block-level storage within the hardware virtualization software, and it must be dedicated to the Exchange guest machine. Exchange 2007 does not support the use of network attached storage, but if the storage is attached at the host level, the guest will see it as local storage. Should you plan to use SCSI or iSCSI in your virtual Exchange environment, Hyper-V only supports VHDs up to 2040 gigabytes (GB) in size, and virtual IDE drives up to 127 GB; plan accordingly.
- Microsoft supports the use of both cluster continuous replication (CCR) and single copy clusters (SCC) within Exchange running in a virtual environment so long as there are no hypervisor-based clustering or migration technologies in use. An example of these technologies would be Quick Migration for Hyper-V and VMotion for VMWare. Likewise, Microsoft does support the use of hypervisor clustering and migration so long as CCR and SCC are not in use within the Exchange environment.
- One of the biggest advantages of virtualization is the ability to take snapshots of your virtual environment as part of a backup or disaster recovery plan. In the Exchange world this can be problematic because this kind of technology is not “application aware.” This means the snapshot technology is not capable of taking into account the way the application actually uses and processes its data. Because of the way Exchange processes data, Microsoft does not support the use of any kind of snapshot technology with your virtual Exchange server. However, it should be noted that in the case of Exchange, the other benefits of virtualization tend to outweigh the inability to use snapshot technology.
- When you are configuring the virtual processors for your Exchange host, it is important to understand that Exchange running in a virtual environment does not support a ratio of greater than 2:1. Hypervisors provide the ability to share the logical processors of the host server to the guest machines. For example, a dual processor system using quad core processors contains a total of eight logical processors in the host. You may have some virtual servers that end up using less processor power than another, so the full processor may not be needed by that server. Depending on the virtual servers, this may allow you to have much more than eight virtual servers configured to have two processors each. However, in the Exchange world, Microsoft would not support the allocation of more than 16 virtual processors across all of the guest machines running on the server, or a total of four quad processor Exchange servers.
Source of Information : Elsevier-Microsoft Virtualization Master Microsoft Server Desktop Application and Presentation
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