Capacity Planning Worksheet

Use the Capacity Planning worksheet to do your production capacity planning. This worksheet requires information from the initial requirements plan and your actual performance test results. For more information on capacity planning and examples using this worksheet, please refer to Chapter 15.

Part 1: Requirements Summary

Part 1 of the Capacity Planning worksheet contains a summary of the key requirements for your web site: load, throughput, and response time. Use this data to help determine your hardware needs.

Part 2: Performance Results Summary

	Input Data	Source of Data	Your Requirement
1.	Concurrent users (with headroom )	Hardware Sizing worksheet, line 7
2.	Response time	Hardware Sizing worksheet, line 4
3.	Throughput (with headroom)	Hardware Sizing worksheet, line 9

Part 2 contains a summary of the final performance test results. Use the final, tuned results from the performance worksheets recorded during the test. Appendix D provides example performance worksheets.

Single-Server Result

Using the performance worksheet or graphs of your test results, locate the performance of a single server corresponding to your response time objective, as specified in line 2 above.

	Response Time (Line 2 Above)	Simulated Load (from Performance Results)	Measured Throughput (from Performance Results)
4.

Cluster Scalability Results

Using the performance worksheet or graphs of your cluster test results, locate the performance of the cluster corresponding to your response time objective, as specified in line 2 above. We recommend doing at least a three-server cluster test. Add more rows to this table for larger tests.

	Number of Application Servers	Response Time (Line 2)	Simulated Loads	Measured Throughput
5.	1
6.	2
7.	3

CPU Utilization Data

From the performance worksheet, locate the CPU utilization for each of the servers during your cluster runs. Make sure to record the CPU utilization for all servers in the test bed. Add more columns for additional servers and more rows for larger cluster tests.

	Number of Application Servers	Application Server CPU	HTTP Server CPU	Load Balancer CPU	Database 1 CPU	Database 2 CPU	Othe r CPU
8.	1
9.	2
10.	3

Part 3: Capacity Planning Estimates

This section estimates hardware requirements for your web site using the data from Parts 1 and 2.

Cluster Scaling Ratio

Calculate the scaling achieved during your cluster runs. You do this by calculating the ratio between the throughput of the cluster and the individual server's performance.

	Number of Application Servers	Measured Throughput	Scaling Rati o Calculation	Scaling Ratio
11.	1		Throughput (1) / Throughput (1) Line 5 / Line 5	1x
12.	2		Throughput (2) / Throughput (1) Line 6 / Line 5
13.	3		Throughput (3) / Throughput (1) Line 7 / Line 5

Estimate Scaling Ratio

This step estimates the scaling ratio as we add additional servers to the cluster. This section of the worksheet assumes that additional servers follow the same scaling pattern measured in the lab. We do not recommend estimating beyond twice the tested performance.

For example, to calculate the scaling ratio for four application servers, take the scaling ratio for three application servers plus the delta between the ratio at three application servers and two application servers. This sum gives us the projected scaling for four servers. Generally, the calculation for the scaling ratio for n number of servers is ratio ( n “ 1) + (ratio ( n “ 1) “ ratio ( n “ 2 )).

	Number of Application Servers (Projected)	Scaling Ratio Calculations	Scaling Ratio Estimate
14.	4	Line 13 + (Line 13 “ Line 12)
15.	5	Line 14 + (Line 14 “ Line 13)
16.	6	Line 15 + (Line 15 “ Line 14)

Estimate Throughput and Load

This step estimates the concurrent users and throughput as you add additional servers to a cluster. The estimated load is a pure linear projection. Derive the estimated throughput using the scaling ratio calculated above. Continue adding servers to your estimate until you meet both the load and throughput requirements.

	Number of Application Servers	Estimated Load (Number of Application Servers * Load, Line 5)	Meets Requirement? (Line 1)	Scaling Ratio	Estimated Throughput (Scaling Ratio * Throughput, Line 5)	Meets Requirement? (Line 3)
17.	4			Line 14
18.	5			Line 15
19.	6			Line 16
The total number of application servers to meet the estimated load and throughput requirement is ______________.

Estimate CPU Utilization

To complete the hardware estimates, consider CPU utilization on all the servers included in your web site. You cannot achieve the application server scaling estimates if other servers' CPU utilization becomes a bottleneck.

CPU Utilization per Additional Server

Calculate the increase in CPU utilization for each type of server as you add more application servers to the test cluster.

	Number of Application Servers	Application Server CPU	HTTP Server CPU	Load Balancer CPU	Database 1 CPU	Database 2 CPU	Other CPU
20.	1
21.	2
22.	3
23.	Delta
24.	4
25.	5
26.	6

HTTP Server CPU Utilization Projections

Estimate the number of HTTP servers required to support the projected load and throughput. This calculation takes the CPU utilization of the preceding cluster run and adds the delta CPU utilization increase anticipated as both the load increases and the cluster adds an additional application server. Once the CPU utilization projections reach 80% or higher, plan to add an additional HTTP server, or to add additional processing power to existing server(s).

	Number of Application Servers	Projected HTTP Server CPU CPU ( n “ 1) + Delta	Add Server (If CPU at 80% or Higher) Yes/No	New Projected Server CPU (If New Server Added)
27.	4
28.	5
29.	6

Database Server CPU Utilization Projections

Estimate the number of database servers required to support the projected load and throughput. This calculation takes the CPU utilization of the preceding cluster runs and adds the delta CPU utilization increase anticipated as the load increases and the cluster adds an application server. Once the projected CPU utilization reaches 80% or higher, plan to split your databases across additional servers or add more processing power to the existing server.

	Number of Application Servers	Projected Database Server CPU CPU ( n “ 1) + Delta	Need to Scale Server (If CPU at 80% or Higher) Yes/No	New Projected Server CPU (If New Server or More Hardware Added)
30.
31.
32.

Other Server Utilization Projections

Follow the same methodology used above for all other servers in your environment.

	Number of Application Servers	Projected Other Server CPU CPU ( n “ 1) + Delta	Need to Scale Server (If CPU at 80% or Higher) Yes/No	New Other Server CPU (If New Server or More Hardware Added)
33.
34.
35.

Summary CPU Utilization Data

	Number of Application Servers	Number of Times to Scale HTTP Servers	Number of Times to Scale Databases	Number of HTTP Servers and CPU Utilization	Number of Database Servers and CPU Utilization
36.