Topic Last Modified: 2005-05-20
When planning a highly available Exchange 2003 environment, consider all available alternatives and measure the risk of failure for each alternative. Begin with your current organization and then implement design changes that increase reliability to varying degrees. Evaluate the costs of each alternative against its risk factors and the impact of downtime to your organization. For a worksheet that can help you evaluate your current environment, see "Checklist for Evaluating Your Environment" in Planning an Exchange Server 2003 Messaging System.
Often, achieving a certain level of availability can be relatively inexpensive, but to go from 98 percent availability to 99 percent, for example, or from 99.9 percent availability to 99.99 percent, can be costly. This is because bringing your organization to the next level of availability may entail a combination of new or costly hardware solutions, additional staff, and support staff for non-peak hours. As you determine how important it is to maintain productivity in your IT environment, consider whether those added days, hours, and minutes of availability are worth the cost.
Every operations center needs a risk management plan. As you assess risks in your Exchange 2003 organization, remember that network and server failures can result in considerable losses. After you evaluate risks versus costs, and after you design and deploy your messaging system, be sure to provide your IT staff with sound guidelines and plans of action in case a failure does occur.
For more information about designing a risk management plan for your Exchange 2003 organization, see the Microsoft Operations Framework (MOF) Web site. The MOF Web site provides complete information about creating and maintaining a flexible risk management plan, with emphasis on change management and physical environment management, in addition to staffing and team role recommendations.