Load Testing Exchange 2000

After you finish adding user groups, save the .sim file—preferably to a file server that you've set up with your installation source files or to a monitoring station that all clients can access. To save the file, select File, Save from the LoadSim menu bar. During the test runs, all clients will access the same .sim file. An important trick is to use the menu bar's File, Save As option to save the file again with a different name. Open the second file, then open the Test Properties dialog box. For each server, remove all the client machines except one and increase the number of users on that client to cover all users on that server. Why? LoadSim's initialization phase creates the mailboxes and populates them with messages, appointments, and contacts. Running the initialization from one client per server causes it to run smoothly. Otherwise, the Exchange server gets hammered processing multiple requests to create and stuff mailboxes and will eventually fail to create all the required items. After you configure all clients for this initialization, save the second LoadSim file.

Open your initial LoadSim file and select Tools, Options from the menu bar. Both sections on the Option dialog box's Logging tab include an Archive previous file check box, which is cleared by default. Select both check boxes, close the dialog box, then save the LoadSim file. The default setting instructs LoadSim to reuse one file to generate output. Assuming that you have a few megabytes of free disk space on your clients, archiving the file will cause LoadSim to rename old output files (appending a number) and generate a new file. Archiving is helpful when you want to make several test runs before you analyze your data—otherwise, you have results only from your final test run.

Populating the Directory
After you define the topology and test properties, you're ready to populate AD with all the necessary DLs and user accounts, then mailbox-enable those objects. From the LoadSim menu bar, select Run, Create Topology. After the progress bar shows that the process is finished, open the Microsoft Management Console (MMC) Active Directory Users and Computers snap-in and look for the Loadsim Users container, which holds additional containers for each server, to verify that the process was successful. If you find errors, delete all users and DLs and repeat the Create Topology process. Be aware that the user accounts won't display Exchange properties (e.g., SMTP addresses) until Exchange 2000's Recipient Update Service (RUS) has a chance to process all the new users. (This process usually takes a few minutes.)

Initializing the Mailboxes
The next step is to stuff your test mailboxes full of mail. To initialize your mailboxes and public folders, open LoadSim on each client that you configured in your second LoadSim file. On each client, select Run, Initialize Test from the LoadSim menu bar. On each client, LoadSim displays a prompt, asking whether you want to initialize public folders. If you initialize from multiple clients, click Yes to accept this prompt on one client and click No to refuse the prompt on the other clients. (Mailbox creation occurs during initialization—mailboxes are created when the first piece of mail arrives rather than when the accounts are created in AD—and is extremely load-intensive on your Exchange servers. If you attempt to run too many clients during the initialization process, you might overload the servers or your network and receive MAPI errors such as Unable to log on.) The initialization process takes several hours at best, so I suggest you run it overnight. If you forgot to enable circular logging earlier (or simply oppose it), be sure to monitor your log-disk space or you'll experience first-hand what happens to Exchange 2000 when the log volumes fill up.

When the initialization is complete, verify the number of items per mailbox. To do so, open the MMC Exchange System Manager snap-in and expand the Servers\Storage Groups\Mailbox Stores\Mailboxes container to see whether all mailboxes contain the same number of items for MMB2. Note that the mailboxes' sizes vary because LoadSim randomizes the attachment mix as it populates the mailboxes.

The initialization process takes a long time. Unless you want to risk having to repeat this step, back up the stores so that you can simply restore from backup before repeating a test run. Turn off circular logging before you create your backup. I typically use Win2K's built-in NT Backup utility to back up the Exchange stores directly to disk. (A minor problem with this backup tool is that you can't remotely back up a server. I log on to the Exchange server locally or through Win2K Server Terminal Services, then schedule and run the backup job from there.)

Capturing Performance Data
While LoadSim is initializing, you can set up your performance-logging environment—the final task before you run the performance test. This procedure contains three steps: Create the capturing log file, open the log-file settings and connect to a server, and add the performance counters to capture data for that server. On your collection workstation, which should run Win2K, launch Performance Monitor, expand the Performance Logs and Alerts node, then right-click the Counter Logs node. Select New Log Settings from the context menu (unless you've already saved some setting during previous monitoring, in which case you need to select New Log Settings From and enter the name of your existing file). Enter a descriptive name (usually the monitored server's name), then click OK to open the settings dialog box.