With the advancement of computer technologies and the World Wide Web, there has been an explosion in the amount of available e-services, most of which represent database processing. Efficient and effective database performance tuning and high availability techniques should be employed to insure that all e-services remain reliable and available all times. To avoid the impacts of database downtime, many corporations have taken interest in database availability. The goal for some is to have continuous availability such that a database server never fails. Other companies require their content to be highly availabile. In such cases, short and planned downtimes would be allowed for maintenance purposes. This chapter is meant to present the definition, the background, and the typical measurement factors of high availability. It also demonstrates some approaches to minimize a database server’s shutdown time.