Some Microsoft® SQL Server™ users require their application databases to be available all the time. However, there is the concern that hardware or system failure could render the databases unavailable. To address this potential problem, SQL Server version 6.5 servers provided failover support, which enables another computer running SQL Server to adopt the crucial databases and device files of a failed primary server. SQL Server’s failover functionality is based on underlying hardware or operating system support for transferring the control of the hard drive array from a primary server to a failover server.