Managing the availability of mission critical systems requires an understanding of the risks and costs of losing access to business critical information or services balanced against the cost of achieving a certain level of availability. That balance is shifting toward higher levels of availability as network services becomes essential to business continuity and the cost of downtime escalates. A February 2004 study by Infonetics Research revealed that interruptions in enterprise availability cost large companies an average of 3.6 percent of annual revenues. As a result, IT managers face growing pressure to drive network availability to unprecedented levels. At the same…