The first article in this series (January 1998) focused on basic LoadSim topics, such as the theory behind LoadSim and the approach you use to test Microsoft Exchange with it. In part two (February 1998), I covered LoadSim installation and configuration. This month, I'll show you how to customize LoadSim, and in my next article, I'll show you how to collect and analyze data.
In part two, I proposed a scenario for walking through LoadSim installation and configuration. For my test scenario, I had two major requirements: First, I wanted to ensure that one server could sufficiently handle 300 users that closely match LoadSim's Medium user profile. Second, I wanted response times of 1 second or less. This value is standard, and users generally don't get impatient if response time stays in this range.
After installation and configuration, you're ready to run the test and start collecting data. For my scenario, you can skip customization because you'll use the default parameters in the Medium user profile. However, you might want to customize the parameters for future tests. In this article, I'll show you how to specify various parameters and settings.
Customizing Tasks
From LoadSim's main menu, go to Configuration, Test Properties to access the test properties. From there, click the Customize button to bring up the Customize Test property sheet, as Screen 1, page 178, shows. You'll see three tabs. The Tasks tab lets you customize the parameters for the various user tasks. The Test/Logon tab lets you configure how the LoadSim user handles logging on and off during the test. The Initialization tab lets you specify how you'll set up the Exchange database during the Initialize Test process.
The tab that you will be most concerned with when customizing LoadSim is the Tasks tab. Screen 1 lists seven tasks that represent activities LoadSim users can perform on the Exchange server. You can enable or disable any of these tasks; simply highlight the desired task and click the Enable/Disable task button. You can set up any task mix you want. In Screen 1, I have four tasks enabled: Send Mail, Process Inbox, Browse Mail, and Schedule+. These are the most common tasks a LoadSim user will perform and probably the tasks your real-world users will perform most often.
The number in the Frequency column represents the number of times per day each LoadSim user will execute each task. For example, my LoadSim users will send mail 4 times a day, process the Inbox (read new mail) 12 times a day, browse existing mail 15 times a day, and perform a Schedule+ action 5 times a day. Note that no public folder activity will occur, and the LoadSim users will not log off Exchange. Let's look at how to configure these values.
Click the Edit Tasks button to see the Task Properties sheet, which Screen 2, page 178, shows. This property sheet has seven tabs that correspond to the seven tasks shown in Screen 1. You can leave the default parameters in the tabs or change the parameters when you want to customize something. Some of the tabs pertain to public folders, which won't concern you for this test because our profile specifies no Public Folder activity.
Screen 2 shows the Send Mail tab. You use this tab to configure the user load as it pertains to sending email. The values in these boxes directly correspond to the values in the Medium user profile. They change as you select the Light, Medium, and Heavy user profiles from the Edit User Group dialog.
The Medium user profile calls for sending new mail four times a day, which the Frequency section reflects. From the Messages button, you configure the messages LoadSim sends. Screen 3 shows the Send Message Options dialog box that appears when you click the Messages button in the Send Mail tab. LoadSim contains a set of default files that comprise the content of messages, but you can create your own LoadSim messages.
When a user composes an email or sends an attachment, LoadSim uses the source files listed in the dialog box. LoadSim pulls the files into the mail messages as necessary. LoadSim assigns a weight to each file, as the Select messages from section of Screen 3 shows. This weight determines how often LoadSim uses the file in email. You can highlight the number in the Weight column and modify the value.
Microsoft used the Exchange client to create each LoadSim file and saved the files in the Exchange client's message format (.msg). This format is specific to Exchange and contains everything in the mail message, including text, formatting, attachments, and embedded objects. Table 1, page 180, describes each file listed in Screen 3. If you're curious, you can open any of these .msg files with the Exchange client or Outlook to see what is in them.
You don't need to specify to LoadSim how many messages have attachments, embedded objects, rich text, and so on. Because the .msg files include these attributes, specifying a weight for each file implicitly determines how often LoadSim will use a message with an attachment or a plain text message.
If the sum of the weights for all the .msg files equals 100 (or a multiple of 10), you can easily calculate how often, in percentage terms, LoadSim uses each file. For example, if a file has a weight of 60 out of a total of 100, LoadSim uses that file 60 percent (60/100) of the time. Notice that in the example in Screen 3, the default Medium user weights add up to 95. Unfortunately, Microsoft ships the profile this way. (The weights for the Light and Heavy profiles add up to 10 and 100, respectively.) So LoadSim sends the file, ups1k.msg, which has a weighting of 60, 64 percent (60/95) of the time. This percentage corresponds directly to the Medium user profile parameters in Table 2, page 181.
You can use your own files in place of the default message files. Simply create them with the Exchange client or Outlook and save each file in message format. Then add them to the message list with the Add Files button and assign a weight. With the remove button, you can remove files you don't want to use anymore.
Finally, the Set priority and Request receipts sections control what percentage of messages have priorities and receipts configured. When you finish working with messages, click OK to return to Screen 2.
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