Developing Availability and Scalability Goals

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Begin establishing goals by reviewing information that is readily available within your organization. Existing Service Level Agreements, for example, define the availability goals for specific IT services or systems. Gather information from those individuals and groups who are most directly affected, such as the users or departments that depend on the services and the people who make decisions about IT staffing.

The following questions provide a starting point for developing a list of availability goals. These goals, and the factors that influence them, vary from organization to organization. By identifying the goals appropriate to your situation, you can clarify your priorities as you work to increase system availability and reliability.

Organization’s Central Purposes

These fundamental questions will help you prioritize the applications and services that are most important to your organization and the extent to which you rely on your IT infrastructure for certain key tasks.

  • What are the organization’s central purposes?

  • What must the organization accomplish to survive and flourish?

Details on Record That Help Define Availability Requirements

The questions in this section can help you quantify your availability needs, which is the first step in addressing those needs.

  • If your organization has attempted to evaluate the need for high availability in the past, do you have existing documents that already outline availability goals?

  • Do you have current or previous Service Level Agreements, Operating Level Agreements, or similar agreements that define service levels?

  • Have you defined acceptable and unacceptable service levels?

  • Do you have data about the cost of outages or the effect of service delays or outages (for example, information about the cost of an outage at 9 A.M. versus the cost of an outage at 9 P.M.)?

  • Do you have any data from groups that practice incident management, problem management, availability management, or similar disciplines?

Users of IT Services

It is important to define the needs of your users to provide them with the availability they need to do their work. There is often a tradeoff between providing high availability and paying the cost of hardware, training, and support. Categorizing your users can make these kinds of business decisions easier.

  • Who are the end users? What groups or categories do they fall into? What expertise levels do they have?

  • How important is each user group or category to the organization’s central goals?

Requirements and Requests of End Users

These questions help pinpoint the needs of your users. You can more easily customize your high availability solutions and anticipate scalability issues if you know exactly what your users need.

  • Among the tasks that users commonly perform, which are the most important to the organization’s central purposes?

  • When end users try to accomplish the most important tasks, what do they expect to see on their screens (or access through some other device)? Described another way, what data (or other resources) do users need to access, and what applications or services do they need when working with that data?

  • For the users and tasks most important to the organization, what defines a satisfactory level of service?

Requirements for User Accounts, Networks, or Similar Types of Infrastructure

It is important to know about supporting services — even services that you do not control — when evaluating availability needs and defining availability goals. Your system will be only as fault tolerant as the systems that support it.

  • What types of network infrastructure and directory services are required so that users can accomplish the tasks that you have identified as requirements for end users? In other words, what types of behind-the-scenes services do users require?

  • For these behind-the-scenes services, what defines the difference between satisfactory and unsatisfactory results for the organization?

Time Requirements and Variations

Keeping support staff on-site to maintain a system can be expensive. Costs can be minimized if support personnel are on-site only during critical periods. Similarly, knowing when workload is highest can help you anticipate when availability is most important, and possibly when a failure is likely to occur.

  • Are services needed on a 24-hours-a-day, 7-days-a-week basis, or on some other schedule (such as 9 A.M. to 5 P.M. on weekdays)?

  • What are the normal variations in load over time?

  • What increments of downtime are significant (for example, five seconds, five minutes, an hour) during peak and nonpeak hours?