Introduction to the HP Virtual Server Environment

Severe Penalty for Underprovisioning
A major reason for overestimating resource requirements is that the impact of undersizing a server
is severe. If a customer purchases a new system that has insufficient resources to meet the
demand for the workload, customers must then:
• Purchase another, larger server, thereby increasing the cost of the project significantly.
• Wait for the new server to arrive.
• Initiate another installation, test, and migration project to move the workload to the new
server.
An even more significant impact is that the organization that designed the original solution loses
credibility, causing future recommendations to be met with skepticism, and resulting in the need to
do more work to justify these recommendations.
Anatomy of a Workload
This section explores the two most common types of workloads -- interactive and batch -- in more
detail.
User-Interactive Workloads
The load on user-interactive workloads is normally very spiky, as illustrated in Figure 1.
Figure 1. CPU usage over time
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Number
of CPUs
Time
The graph in Figure 1 shows a real workload in the HP IT infrastructure and represents a web-
based application on the www.hp.com portal. Because this is a revenue-generating workload, it
is critical that it does not experience performance problems when it is under heavy load. As a
result, the server that this workload runs on must be able to handle the peak load. If this
workload were running on a fixed-size server or partition, it would need a minimum of 6 CPUs.
However, the average load on this workload is only about 1.5 CPUs. This results in a 25%
average utilization.
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