Lab 7.1: Planning CPU and Bandwidth Capacity

After completing this lab, you’ll be able to

• Calculate the CPU usage and bandwidth usage per user
• Determine the number of Web servers and CPUs necessary to support your users
• Determine the capacity of your network bandwidth

About This Lab

In this lab you’ll determine the capacity requirements for your network. You’ll be focused specifically on CPU capacity (and the number of Web servers) and the capacity supported by your network bandwidth.

Before You Begin

Before you begin this lab, you must be able to

• Administer Windows 2000 Advanced Server
• Understand basic network and computer concepts related to user capacity

Scenario: Capacity Planning for Adventure Works

Adventure Works is a nationwide tour company that provides vacation packages to clients traveling around the world. The company is upgrading its Web services so that clients will be able to log on to the site so that they can receive information about packages customized to their specific needs. Until now users were simply able to access the site to view information about the various packages. To deliver the new services, administrators will be implementing a SQL Server back end. ASP will be used to access and display data from the database. The Adventure Works network is a 100-Mbps Ethernet network. Figure 7.10 provides an overview of the company’s network topology.

Normally, the site services about 1,000 to 3,000 concurrent users, although at peak times that number can increase to up to 6,000 users. The company doesn’t anticipate that the number of users will increase too greatly when the new services are implemented. The Web servers are each configured with three 400 MHz processors. The upper bound per computer is 755 MHz. As the administrator, you must determine the number of processors necessary to support the current usage and you must assess how much capacity the network supports.

Figure 7.10 - The network topology of Adventure Works

Exercise 1: Identifying the User Base

In this exercise you must identify the number of concurrent users on which to base your capacity calculations. From there you must calculate the CPU and network costs per operation.

1. How many concurrent users should your network support?

Once you’ve determined the number of users, you can then calculate the CPU usage per users. The first step in performing these calculations is to identify the applicable operations and the data about each of those operations. Based on your analysis, you’ve identified the operations and necessary information about each operation (shown in Table 7.12).

Table 7.12 Operations in the Adventure Works Network

Operation	CPU Utilization	Requests per Second	Request per Operation	Operations per Second
Default	96.15%	96.98	1	0.00128
Add Item	92.08%	26.21	3	0.00102
Listing	93.42%	29.29	2	0.00329
Lookup	98.99%	82.08	2	0.00121

2. What’s the first step you must take to calculate the CPU usage per user?
3. What’s the next step that you should take to calculate the CPU usage per user?
4. What’s the CPU cost for each operation?
5. Once you’ve determined the cost per operation, you can determine the cost per user per operation, and from there, determine the cost per user. What’s the cost per user for each operation?
6. What’s the total cost per user for CPU usage?

Now that you’ve determined the CPU usage per user, you can determine the network usage per user. Based on your analysis, you’ve identified the necessary information about each operation (shown in Table 7.13).

Table 7.13 Network Costs of Operations

Operation	Operations per Second	Web Network Costs	Data Network Costs
Default	0.003682	1.845	0
Add Item	0.000254	4.978	127.756
Listing	0.000523	26.765	24.123
Lookup	0.001134	25.678	25.564

7. Your first step is to calculate the network costs per operation. What’s the network cost for the Default operation?
8. What are the network costs of the remaining three operations?
9. What are the total network costs per user?

Exercise 2: Determining CPU Requirements

In this exercise you’ll determine how many Web servers you need in order to support the current number of users. You’ll base your calculations on the costs per user that you determined in Exercise 1. At this point you should have all the base information that you need to calculate your CPU requirements.

1. How much processing power does each server have and how much of that can be used?
2. What is the total cost per user for CPU usage?
3. How many concurrent users can the CPUs in each Web server support?
4. Once you’ve determined how many concurrent users each machine will support, you should round down that amount to a whole number and use that figure to calculate the number of servers that you need. How many Web servers should your cluster contain?

Exercise 3: Determining Bandwidth Capacity

In this exercise you’ll calculate whether your current network can support the number of concurrent users. You’ll base your calculations on the costs per user that you determined in Exercise 1. At this point you should have all the information you need to make these calculations.

1. What’s the network bandwidth and how much of that bandwidth should you utilize when planning your capacity requirements?
2. How many concurrent users will your network support?