On a daily basis, system and network administrators are faced with a new challenge by hitting the same point: we are aiming to make our infrastructure highly available!

Meanwhile, the IT manager sticks to his chair, drinking his tea and claims: our IT system works just fine and our customers are satisfied. Surprisingly, you get that phone call from the help desk with a struggling voice: well, the browser said "page not found". Is the application server down? Obviously, the infrastructure was not as highly available as it should have been. Despite your extra time spent configuring clusters to be in uptime, more often than not, servers might not be reachable and you then face a few special events, and you raise this question: why does it not fail over? To make sense of an HA infrastructure, on one hand, you should know what HA offers to your environment and how. On the other hand, you should stay close to test scenarios of failing over as exemplified in the following real...