Understanding Exchange Performance
Applies to: Exchange Server 2010
Topic Last Modified: 2010-01-26
Tuning a system for optimum performance is an iterative process. You must take the time to understand all the variables that affect your system, including user profile, architecture, and hardware. With this knowledge, you can establish baseline metrics for your systems and make adjustments to improve system performance.
Generally, the maximum level performance for a server is determined by the component that has the lowest performance—the bottleneck in the system. The key to improving performance is being able to identify bottlenecks, determine their cause, and take the appropriate corrective action.
As you plan your Microsoft Exchange Server 2010 deployment, you can use the topics in this section to help design and optimize your environment for high performance:
Understanding Processor Configurations and Exchange Performance
Understanding Memory Configurations and Exchange Performance
Understanding Server Role Ratios and Exchange Performance
Understanding Multiple Server Role Configurations in Capacity Planning
Understanding Client Access and Hub Transport Combined Role Configurations in Capacity Planning
The concept of performance is closely related to the concept of scalability. When you have a solid understanding of the factors influencing the performance of system components, you can deploy components in a way that scales to support periods of high demand.
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Several tools for measuring performance are available for use with Exchange 2010, including Jetstress and Load Generator (LoadGen). The Windows Server 2008 operating system also includes some general performance tools including Windows Performance Monitor.
In addition to these tools, you should analyze your current user loads to establish a minimum server requirements baseline. Understanding how your users use the system is one of your biggest challenges. The Exchange Server Profile Analyzer can help provide useful data when analyzing your current user loads. After you determine your hardware requirements, you should conduct a pilot test to make sure performance levels are acceptable.
For more information, see Tools for Performance and Scalability Evaluation.
When selecting hardware for your Exchange servers, there are many things that you must consider. The hardware that you select for your Exchange deployment has the greatest effect on performance. Two of the most critical resources to evaluate are processor and memory. Because of the large number of variables that affect performance, it's difficult to predict the effects of high server utilization on the performance of any particular hardware component. The following definitions apply to the terms minimum, maximum, and recommended:
Minimum This is the minimum processor and memory configuration suitable for specific Exchange 2010 server roles (also defined in system requirements). Minimum hardware requirements must be met to receive Microsoft Customer Service and Support.
Maximum This is the maximum recommended processor and memory configuration for specific Exchange 2010 server roles. Maximum is defined as the upper bound of viable processor and memory configurations for Exchange 2010 based on price and performance. Maximum is a guideline and not a support criterion. It doesn't take into account the resource requirements of third-party applications. The recommended maximum may change over time based on price changes and technology advancements.
Recommended This is the recommended processor and memory configuration for specific Exchange 2010 server roles. Recommended can be 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 utilize the processors without becoming bottlenecked on memory or vice versa.
Exchange 2010 benefits significantly when running on multi-core processors. The performance benefit for Exchange from multi-core technology depends upon the specific processor utilized. Multi-core processors are an attractive option for Exchange 2010 servers based on price and performance. It's important to consult with your server hardware vendor about multi-core benefits for Exchange, specific to a given hardware architecture.
The processor usage on a server should maintain a load of about 60 percent during peak working hours. This percentage level allows room for periods of extreme load. If the processor usage is consistently greater than 75 percent, processor performance is considered a bottleneck.
There are several factors by which the CPU in a server affects performance. These include:
The processor clock speed, measured in megahertz (MHz) or gigahertz (GHz)
The number of processors
The type of processor
For performance, selecting the fastest processor yields the best results. However, budget and cost dictate most companies' choices.
Exchange can fully use multiple processors, and using servers with more processors improves performance. However, the relationship between the number of processors, number of processor cores, and performance is complex. The optimum number of processors and cores is partly determined by the Exchange role deployed on the server.
For more information about how different processors perform, see Understanding Processor Configurations and Exchange Performance.
After the required number of processor cores has been estimated for a specific server role, baseline memory recommendations can be applied. Exchange 2010 on the 64-bit editions of the Windows Server 2008 operating system can efficiently utilize upwards of 64 GB of memory (Mailbox server role).
With effective planning and an understanding of the basic processor and memory requirements for specific Exchange 2010 server roles, a balanced and cost-effective topology can be attained.
For more information about how different memory configurations perform, see Understanding Memory Configurations and Exchange Performance.
Much of the network interface subsystem is tuned automatically. Server-based network adapters are capable of detecting the type and level of traffic passing through the network interface, and they self-tune to reflect this information. We recommend that you have operational practices in place to ensure that the latest device drivers are maintained on the server.
For Mailbox servers, gigabit Ethernet (1,000 megabits per second (Mbps) or 1 gigabit per second (Gbps)) is recommended.
Multiple switched fast Ethernet networks of gigabit Ethernet connections are recommended.
Performance-related issues may arise because your hardware, firmware, or software drivers aren't designed to work in your configuration. For more information, see the Products Designed for Microsoft Windows Web site.
As storage requirements increase and companies consolidate servers, you must balance cost, availability, and performance when you design a storage system. Take time to invest in good storage design before you implement it. Unlike processors and memory, which you can scale while the network is active, storage redesign requires network downtime to implement. Tuning your Exchange storage becomes a critical component in the overall performance of your Exchange environment.
There are a few guidelines that can be followed for selecting a storage configuration that provides good performance and a strong platform for Exchange 2010. Capacity and performance are often at odds with each other when it comes to selecting a storage solution, and both must be considered before making a purchase. Generally, the decision involves analysis of the following factors:
Making sure there will be enough space to store all of the data. Determining your capacity needs is a relatively straightforward process.
Making sure the solution provides acceptable disk latency and a responsive user experience. This is determined by measuring or predicting transactional input/output (I/O) delivered by the solution.
Making sure that non-transactional I/O has both enough time to complete and enough disk throughput to meet your service level agreements (SLAs).
The goal is to find a balance of these factors so that you can design the actual hardware solution for your servers.
For more information about choosing a storage solution for Exchange 2010, see Mailbox Server Storage Design.