NSI Software's Double-Take, Microsoft's SQL Server, and BakBone's NetVault are among products highlighted in a discussion of Suffolk University of Boston, Massachusetts, backup tools for a virtual e-learning system from Blackboard. The school used ESX Server from VMware to create a set of five virtual machines that run on ProLiant servers from Hewlett-Packard (HP) to provide a level of redundancy. However, the school needed more, and a standard backup application was insufficient due to issues with open files and CPU spikes. Online technical director Praneeth Machettira chose Double-Take to provide full replication in real-time of all activity occurring on the virtual servers. The usual load balancing, clustering, and tape backup methods are not sufficient, but with a combination of virtualization and replication, Blackboard can be up and running in three to five minutes after a server goes down. Many others are also choosing server virtualization, and IDC has estimated that more than 75 percent of companies that have 500 or more employees use virtual servers. Forty-five percent of all new servers purchased in 2006 will be virtualized, including installations for two- and four-way Linux and Windows servers. Backup software vendors are also developing new tools that address the new environments with features for conflict avoidance and resource speed-bumps when multiple virtual servers try to use the same hardware. Companies are finding that a multilayered approach is needed to provide sufficient uptime and reliability.