Performance Management | Microsoft Application Center 2000 Resource Kit 2001

When dealing with performance management, we're talking about the continuous process of evaluating a server to determine whether or not it can deliver the level of performance that's required, which is to say, the server's ability to handle a certain load of concurrent users. Performance management is closed linked to capacity planning; the difference is that performance management involves tuning the current system so that it can perform better, thereby enabling it to support more users. Capacity planning, on the other hand, focuses on how many users a site can support and how to scale the site so it can support more users.

While confronting the myriad of elements that make up a production system, you also have to balance the goals and priorities of two viewpoints—that of the user and that of the administrator. Although it often seems like users and administrators have conflicting views, both want the same things from a system. They want the system to provide good performance, they want the applications to work, and they want the site to be up all the time. It's really a matter of perspective; users and administrators simply have slightly different ways of viewing system goals and interpreting performance.

The User's Perspective

For most users, performance equates to speed—the perceived response time of the system they're using. When they activate a hyperlink and the requested page is retrieved and displayed quickly—typically in less than 10 seconds—their perception of performance is favorable. (It's interesting to note that it's not uncommon for a user to think that a page takes longer to retrieve and display than it actually does.)

From a user's perspective, the definition of performance and the primary goal of performance tuning is the same—make it fast. This speed-based viewpoint encompasses the following:

Initialization
Shut down
Page retrieval and rendering
Reasonable time-outs

The Administrator's Perspective

From an administrator's viewpoint, performance is a measure of how system resources are utilized by all the running programs. The scope of resource usage ranges from the lowest level program (drivers, for example) up to and including the applications that are hosted on a server.

In terms of performance tuning, the administrator's primary goal is to make the system satisfy client requests quickly and without errors or interrupts. His secondary tuning goals are:

Conserving bandwidth
Conserving CPU resources and RAM utilization

NOTE
An indirect goal is eliminating or reducing Help Desk calls, a goal that is usually achieved by meeting the direct goals.

Unlike the user, who deals primarily with perception, the administrator can quantify resource utilization through the collection, observation, and analysis of performance data (see Figure 10.1).

You can use performance data to:

Observe changes and trends in resource usage and workload distribution.
Quantify the relationship between the workload and its effect on system resources.
Test configuration changes or tuning efforts by monitoring the results.

Regardless of the perspective you take, you have to approach tuning systematically and employ a methodology for implementing and testing system configuration changes.

The business perspective

The business perspective also plays a significant role in performance management. In this context, someone has to do determine how much hardware is required, how to make provisions for peak loads, how to balance out spikes with low overall load, and how to determine or satisfy service-level agreements.

It's often necessary to make price and performance trade-offs—it may be too expensive to have enough servers for maintaining low processor utilization at all times, so low average utilization with spikes becomes acceptable.