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If you ranked certain cloud features by the total revenue they could generate or the total user spending they could affect, cloud bursting and failover would be at the top of both lists. Many enterprises consider these two features equally important and find that the processes can support each other. In fact, the best strategy for hybrid cloud deployment is to combine cloud bursting and failover.
Cloud bursting, or workload overflow processing, occurs when an application's presented workload exceeds its capacity. It allows an enterprise to spin up additional instances of the application in the cloud to relieve what might otherwise be a detriment to workers' quality of experience. It's a perfect example of how public cloud resources can augment internal IT resources, and it makes economic sense if it avoids costly capacity oversupply in the data center.
Cloud bursting requires two key technical elements: an application design that permits multiple instances to run at a time, and a mechanism to load balancing work among all the instances -- whether they're running in the data center or the public cloud.
Failover, or disaster recovery, in the cloud also makes sense to buyers. Many enterprises already have considered or partially implemented standby data centers to keep their applications running in case a major failure disables some or all of the normal data center resources.
In a failover strategy, the emphasis is often on major incidents, such as hurricanes or power failures that take out an entire geographic area. In many cases, there's an expected outage period while an enterprise shifts from its primary resources to the standby. In most cases, the applications will be running in one place or the other and traditional mechanisms such as the domain name system (DNS) can redirect work to the standby data center on a failure -- then back to the production data center when the failure has passed.
Clearly, cloud bursting represents a more agile approach for a disaster strategy. If growth in an application's workload can trigger cloud bursting, a reduction in available resources to the application -- server or even data center failure -- could also trigger it. This DR strategy could deal with not only a complete data center failure but also limited equipment, software or even network failures. Overall, successful cloud bursting is a useful strategy for building hybrid cloud applications.
Creating a robust cloud bursting implementation
Issues associated with resource failures, not growth in application workloads, help determine whether cloud bursting can work to build hybrid apps. Users need access to any additional copies of an application, and the copies require access to databases and other resources. Are both of these conditions possible using cloud bursting in disaster recovery mode?