Model Wizard Walk-Through
Before running the Model Wizard, you need to gather some information. You should have a good idea of what hardware you're thinking about purchasing. You need to know the processor and disk configurations of any existing Exchange servers as well as the topology of the Exchange organization. You also need to have some message statistics on hand, along with information about mailbox sizes and usage patterns. If you're planning for a new deployment, you'll have to make educated guesses as to these factors.
When you launch Capacity Planner, you'll see a warning message stating that the software is intended to assist the user in making decisions concerning computer hardware selection and deployment but that it shouldn't be used as the sole basis for decision making. Click OK to clear this message, and you'll see the tool's Welcome screen. Toward the middle of the screen is a drop-down list that lets you select the application you want to model. Select the Microsoft Exchange Server 2003 option from the list, then click the Create a Model with the Model Wizard link.
The next screen asks you to specify both the number of central sites and the number of branch sites in your Exchange organization. Capacity Planner considers central sites to be servers in the main office, whereas branch sites are servers separated from the main office by a WAN link. You also select the type and amount of bandwidth that's typically available between sites, as Figure 1 shows. Because you don't want Exchange consuming all the available bandwidth between sites, you select the maximum percentage of bandwidth that you'll allow Exchange to use. The default is 70 percent.
Click Next, and you see a screen similar to the one that Figure 2 shows. This screen asks you to specify the number of users in the central site and in the branch sites; Capacity Planner allows for only a hub-and-spoke type of network organization. You must also specify what type of mail client is being used in branch sites. The Model Wizard assumes that an equal number of users exist in each branch site; likewise, it assumes that every user in each branch site will use the same type of mail client. These options are examples of the wizard's oversimplification, but you can change them later in the Model Editor.
The wizard's next screen asks you to describe the typical level of mail-server usage across your Exchange organization: Is it typically low, medium, or high? From what I've gathered, these levels are fairly subjective: They give you a starting place, and you can adjust the actual number later when you fine-tune the model. You also enter the average size of each mailbox, the average number of messages that users receive daily, the average number of messages users send each day, and the average size of each message.
Click Next, and you see the screen that Figure 3 shows, which asks you to select a CPU configuration (e.g., one-, two-, or four-processor). You must select at least one CPU configuration, although you can choose up to three. Choosing multiple CPU configurations lets you simulate the differences that a low-, medium-, or high-end configuration would make in your Exchange organization's performance.
By default, the ModelWizard creates a separate server for each Exchange role. In the real world, however, it's sometimes possible to consolidate multiple roles onto a single server. If you want the wizard to consolidate roles when possible, select the Attempt to consolidate roles on to one server check box.
The bottom portion of this screen asks you to select the disk configuration. You can choose from a wide variety of configurations, but whichever type you choose, the Model Wizard will assume that every server in the model uses the same type. Of course, you can change the disk configuration later by using the Model Editor. You can also choose to model a SAN rather than a typical disk configuration; you can adjust SAN variables such as interconnect speed, interconnect count, and the volume configuration when you fine-tune the model. If you use a standard disk configuration, the wizard will automatically determine the minimum number of disks needed for each server.
Click Next, and you see a summary of some of the configuration options you selected with the wizard. The Model Summary screen displays information related to the topology in general and to the servers in the central site; it doesn't include any information related to servers in the branch sites.
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