Prepare for Exchange Server 2010's hardware and software requirements

Exchange 2010 is out and about and ready to deploy. Scott Lowe provides you with some assistance on getting prepared for this latest release in the Exchange line.

With a plethora of new and enhanced capabilities, Exchange 2010 is well worth a look. Whether you're just evaluating the software or preparing for an official rollout, there are a number of hardware and software prerequisites that you need to consider in order for your deployment to be successful.

Hardware requirements

Although Microsoft has taken steps toward reducing Exchange's overall footprint in Exchange 2010 (particularly when it comes to I/O), the product still requires significant resources, including a large amount of RAM and disk space. Processing power is also a concern since the server needs to be able to keep up with its workload.

From a processing and operating system perspective, keep in mind that Exchange 2010, like Exchange 2007, supports only 64-bit processors and operating systems. Any recent x64 processor, with the exception of Itanium models, will be sufficient, but faster is better, and more cores equals more processing power. However, you don't want to seriously overbuild servers, as those unused cycles cost money.

On the RAM side, Exchange is hungry, but it uses everything you throw at it -- at least to a point. Some Exchange administrators get nervous when they check Exchange's memory usage and see that the information store process is eating up almost all available RAM, but this is by design; the store process caches everything it can in order to improve the overall system performance. (The associated download provides a minimum and a maximum value for RAM on each component, which is intentional; Microsoft recommends that you do not exceed the maximum value, as doing so can have a negative impact on server performance.)

Exchange hardware requirements vary greatly depending on the size of the environment. From single server/multi-role environments using a few dozen gigabytes of space to environments made of up dozens of servers and using hundreds of terabytes of space, Exchange is far from a one-size-fits-all solution; that said, you have to start somewhere with your calculations.

Associated with this article is a download that provides you with a starting point in your Exchange RAM and processor calculations. The download is broken down into these six columns:

  • Component mix. Which components are being installed side-by-side on the target server?
  • Minimum/maximum RAM. Shows the recommended minimum and maximum amounts of memory that should be installed to support the needs of the installed roles.
  • Minimum/Recommended/Maximum Processor. Gives you a look at the minimum, recommended, and maximum cores that are necessary to support a particular combination of roles.
  • Disk Information. Provides you with general guidance regarding the performance and the capacity needs for a particular role or role combination. Note that a "Low" entry doesn't mean that you should ignore a particular item; it means that the disk subsystem is a little less critical for that particular role and is not generally a bottleneck.
  • Windows Server 2008 SP2. Identifies the prerequisite software and Command Prompt commands necessary to meet the needs of a particular role combination when those roles are being deployed to a Windows Server 2008 SP2 computer. Make sure that you run the command prompt with administrator rights.
  • Windows Server 2008 R2. Identifies the prerequisite software and PowerShell commands necessary to meet the needs of a particular role combination when those roles are being deployed to a Windows Server 2008 R2 computer. Make sure that you run PowerShell with administrative rights.

For more precision and to move beyond basic environments, make sure to use the constantly refined Exchange 2010 Mailbox Server Role Requirements Calculator. This calculator only helps you fully build the mailbox server, but since the mailbox server is arguably the most important and most foundational Exchange 2010 role, it deserves more attention.

For disk space in the mailbox server, always use the calculator; the Exchange Server team does a tremendous job of making sure that all of the variables are considered in an Exchange disk subsystem, including capacity needs, overall disk subsystem performance requirements, data availability requirements, and a lot more. Bear in mind that it's not just the mailbox role that needs storage attention, though; the other roles also require at least a cursory glance at both capacity and storage performance.

Of the roles, the Client Access server role requires the least effort, with Microsoft's guidance mainly advising that the Client Access role has "a small disk input/output (I/O) footprint." The linked document outlines testing that Microsoft has performed that backs up its guidance. Client Access servers in Exchange 2010 do much more work than the Exchange 2007 Client Access role, and there will be quite a few log files associated with the activity, but the overall impact from a performance perspective is nothing beyond what you'd see in a typical server application.

Transport servers, including the Hub Transport and Edge Transport servers, are more I/O bound, however. Every message sent through an Exchange organization hits a hub transport server at some point, which means that undersized servers can create a bottleneck situation; as a result, Microsoft provides more substantial storage guidance for transport servers.  For transport servers, you need to consider capacity and disk system performance (IOPS).

Software requirements

All of the Exchange Server 2010 roles have prerequisites. Before you can deploy any role, you need to make sure that these requirements are satisfied. The associated download includes the ServerManagerCmd commands and the PowerShell commands necessary to install many of the Windows-based prerequisites.

The associated download file includes all of the links and commands necessary to install the prerequisites for each version of Windows (2008 SP2 or 2008 R2) and for each Exchange role. In the Windows Server 2008 SP2 column, notice that the ServerManagerCmd command uses different XML files depending on what kind of server you're trying to install. These XML files are located on the Exchange Server 2010 media in the Scripts folder.  When it comes time to install a role, make sure you have your Exchange media available so you can use these scripts to install the prerequisites.

If you intend to run Exchange 2010 on a virtualization platform such as VMware vSphere or Microsoft Hyper-V R2, be aware that Microsoft's testing concludes that virtualization overhead equals about 12% and that not all roles are supported in this manner. In particular, the Unified Messaging Server role is not supported in a virtual environment due to its reliance on time-sensitive, real-time communications. Further, not all hypervisors are supported. Fortunately, Microsoft does support the most common virtualization platforms, including its Hyper-V R2, VMware's ESX/vSphere, and Citrix's XenServer. For more information about Microsoft's virtualization support policy, visit the knowledgebase article Support policy for Microsoft software running in non-Microsoft hardware virtualization software.

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By Scott Lowe

Since 1994, Scott Lowe has been providing technology solutions to a variety of organizations. After spending 10 years in multiple CIO roles, Scott is now an independent consultant, blogger, author, owner of The 1610 Group, and a Senior IT Executive w...