10 Mistakes Made by Too Many Disaster Recovery Teams - Slide 9

Many factors can cause site-wide failures, including an air conditioning failure or leaking roof, a power failure, or a major hurricane. Site disruptions can last anywhere from a few hours to days or even weeks. There are two methods for replicating data across sites. One method is to tightly couple redundant servers across high speed/low latency links, to provide zero data-loss and zero downtime. The other method is to loosely couple redundant servers over medium speed/higher latency/greater distance lines. This provides a disaster recovery capability where a remote server can be restarted with a copy of the application database missing only the last few updates. In the latter case, asynchronous data replication maintains a backup copy of the database.