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This topic's current status is: Editing.]
Applies to: Exchange Server 2010
Topic Last Modified: 2009-10-16
There are many factors to consider when selecting hardware for use by Exchange 2010. Three of the most critical factors to consider are choice of processor, amount of memory, and selection of storage. This topic provides guidelines for processor configurations that provide good performance and a strong platform for Exchange Server. For detailed guidance and recommended configurations for memory, see Understanding Memory Configurations and Exchange Performance.
Selecting the Appropriate Processor
For production environments, you must choose a processor that will work with the x64-based version of Windows Server:
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The release to manufacturing (RTM) version of Microsoft Exchange 2010 is only supported in production environments when the x64 version of Exchange 2010 is installed on a computer with x64-compatible processors that is running the Windows Server 2008 x64 Edition operating system.
You can select processors from Intel that support Intel Extended Memory 64 Technology or processors from AMD that support AMD64. For more information about these processor options, see the Intel 64 Architecture Web site or the AMD Opteron Processor Family Web site at http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_8825,00.htm.
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The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.
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Itanium processors cannot be used and are not supported for Exchange 2010. Exchange 2010 is designed to run only on x64-capable processors such as those listed previously, and it will not run on Itanium-based systems.
Regardless of which processor you choose, the server product must have the Designed for Windows logo to be supported. For more information, see Windows Logo Program and Driver Signing: Overview. To ensure support, you must select a server that is listed in the Windows Server Catalog. If your server is not listed, you should verify with the hardware vendor that testing is in progress.
Recommended Processor Configurations
You can use the following table to assist you in purchasing server hardware for Exchange 2010. This table provides minimum requirements, recommended requirements, and recommended maximum configurations for Exchange 2010.
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The following guidance assumes an average concurrency profile. Concurrency is defined as the percentage of the total number of users on a server that are connected and using the server at a specific peak period of time. For a fully utilized server, concurrency is generally in the 75 to 80 percent range.
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The following describes the minimum requirements, recommended requirements, and recommended maximum configurations:
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Minimum This is the minimum processor and memory configuration suitable for specific server roles. The minimum hardware requirements must be met to receive support from Microsoft Product Support Services.
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Maximum This is the maximum recommended processor and memory configuration for specific server roles. Maximum is defined as the upper bound of viable processor and memory configurations based on price and performance. The recommended maximum configuration is a guideline. It is not a support criterion, and it does not take into account the resource requirements of third-party applications that might access or be installed on the server. The recommended maximum configuration may change over time based on price changes and technology advancements.
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Recommended This is the recommended processor and memory configuration for specific server roles. Recommended is defined as the best configuration based on price and performance. The recommended configuration also provides a balance between processor and memory capacity. The goal is to match the memory configuration to the processor configuration so the system will effectively use the processors without becoming bottlenecked on memory and vice versa.
Processor configurations for Exchange 2010 server roles
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Exchange 2010 server role
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Minimum
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Maximum
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Recommended
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Edge Transport
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1 x processor core
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12 x processor cores
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4 x processor cores
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Hub Transport
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1 x processor core
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12 x processor cores
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4 x processor cores
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Client Access
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2 x processor core
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12 x processor cores
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8 x processor cores
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Unified Messaging
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2 x processor core
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12 x processor cores
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8 x processor cores
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Mailbox
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2 x processor core
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12 x processor cores
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8 x processor cores
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Multiple server roles (combinations of Hub Transport, Client Access, and Mailbox server roles)
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2 x processor cores
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24 x processor cores
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8 x processor cores
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The chart above contains recommendations based on the Exchange 2010 feature, RPC Client Access. This feature requires a larger memory and processor configuration to manage the increase loads placed on the Client Access server role. The RPC Client Access feature is enabled by default.
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The Unified Messaging processor recommendations listed above are based on Unified Messaging being deployed with the default configuration which includes the Voice Mail Preview enabled. If Voice Mail Preview is not enabled, the above configurations can be reduced to Minimum 2 x processor core, Recommended 4 x processor core, and Maximum 8 x processor core for the Unified Messaging role.
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Ratings available at the Standard Performance Evaluation Corporation Web site may be used to rationalize unlike processor and server configurations. The third-party Web site information in this topic is provided to help you find the technical information you need. The URLs are subject to change without notice.
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Edge Transport Server Role
The Edge Transport server role information will be provided in a later revision of this document.
Hub Transport Server Role
The recommended configuration for the Hub Transport server role is 4 x processor cores in organizations where Hub Transport servers are deployed with several Mailbox servers and thousands of mailboxes. 8 x processor core servers can be efficiently used when the Hub Transport server is configured to use antivirus and anti-spam. Either 1 x or 2 x processor core configurations can be considered for organizations where there are not enough mailboxes or insufficient message traffic to warrant using a 4 x processor core configuration. Processor utilization is based on several factors such as message rate, average message size, number of enabled transport agents, antivirus configuration, and third-party applications.
Client Access Server Role
Exchange 2010 architecture has moved most of the client-specific functions from the Mailbox server to the Client Access server. In Exchange 2010, messages are converted on the Client Access server when they are accessed by a non-MAPI client (for example, POP3 and IMAP4 clients). In addition, rendering for Microsoft Outlook Web Access is performed on the Client Access server, as opposed to the Microsoft Exchange Information Store service in previous versions of Exchange Server. These architectural changes allow the Client Access server to offload significant processing from the Mailbox server and enable the Client Access server to effectively utilize 4 x processor cores. Servers with 2 x processor cores can be utilized for Client Access servers in organizations where there are not enough mailboxes or insufficient non-MAPI client traffic to warrant using 4 x processor core servers.
Unified Messaging Server Role
The recommended configuration for the Unified Messaging server role is 8 x processor cores. Multiple cores are used on the Unified Messaging server for several architectural functions such as .wav to Microsoft Windows Media Audio (WMA) conversions for voice mail messages. Servers with 2 x processor cores can be used for Unified Messaging servers in organizations where there are not enough mailboxes or insufficient Unified Messaging server activity to warrant using 8 x processor core servers.
Mailbox Server Role
The recommended configuration for the Mailbox server role is based predominantly on mailbox count and user profile. A 4 x processor core server provides a good balance between price and performance, and should be able to host several thousand mailboxes. Sizing for the Mailbox server requires an understanding of the average client user profile. This profile can be collected using the Microsoft Exchange Server Profile Analyzer or by using third-party tools. For more information, see the Microsoft Exchange Server Profile Analyzer Web site. The following table lists generic and common knowledge worker profiles for Microsoft Outlook clients.
Knowledge worker profiles for Outlook users
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User type (usage profile)
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Send/receive per dayapproximately 50-kilobyte (KB) message size
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Light
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5 sent/20 received
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Average
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10 sent/40 received
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Heavy
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20 sent/80 received
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Very heavy
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30 sent/120 received
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There are several factors to consider when sizing Mailbox servers other than the user types listed earlier. These include Mailbox servers that are accessed by Microsoft Forefront Security for Exchange Server, third-party applications, mobile devices, and online (versus Cached Exchange Mode) Outlook clients. Sizing used primarily for budgeting purposes can be accomplished by assuming that 1,000 active average profile mailboxes will require a 1 x processor core (for example, a 4,000-mailbox server with an average usage profile requires 4 x processor cores). A heavy usage profile requires more processor cycles than an average profile, thus for planning purposes use 750 active heavy profile mailboxes per processor core. Therefore, a 6,000-mailbox server with a heavy profile requires an 8 x processor core server. The maximum number of processor cores efficiently used by the Mailbox server role is eight. Deploying mailboxes on servers with more than eight cores will not provide significant scalability improvements.
Multiple Server Roles
To accommodate the Client Access and Hub Transport server roles on the same server as the Mailbox server role, reduce the 1,000 mailboxes per core calculation based on the average client profile to 500 mailboxes per core when performing sizing. As a general guideline, a multi-role server should be sized to use half of the available processor cores for the Mailbox role and the other half for the Client Access and Hub Transport roles. The maximum recommended processor core configuration is listed at 16 x processor cores for the multiple server roles configuration to indirectly provide guidance on the maximum number of users that should be hosted on a multiple role server. Although this configuration can use more than 16 processor cores, we do not recommend this configuration.