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Chapter 2: Disaster RecoveryMinimizing the Chances for a DisasterA single-point failure is when the failure of one component causes the entire system to fail.To minimize single-point failure: Identify conditions where a single-point failure can occur Anticipate what will happen if this component or process fails Eliminate as many of these single points of failure as practical.Practical is defined as the level of work involved or cost compared to the level of riskand failure.Types of single points of failure include: The backup R/3 server is located in the same data center as the production R/3 server.If the data center is destroyed, the backup server is also destroyed. All the R/3 servers are on a single electrical circuit.If the circuit breaker opens, everything on that circuit loses power, and all the serverswill crash.A cascade failure is when one failure triggers additional failures, which increases thecomplexity of a problem. The recovery involves the coordinated fixing of many problems. 1. A power failure in the air conditioning system causes an environmental (airconditioning) failure in the server room.2. Without cooling, the temperature in the server room rises above the equipment’sacceptable operating temperature.3. The overheating causes a hardware failure in the server.4. The hardware failure causes a database corruption.In addition, overheating can damage many things, such as: Network equipment Phone system Other serversThe recovery becomes complex because: Fixing one problem may uncover other problems or damaged equipment. Certain items cannot be tested or fixed until other equipment is operational.In this case, a system that monitors the air conditioning system or the temperature in theserver room could alert the appropriate employees before the temperature in the serverroom becomes too hot.2–18Release 4.6 A/B