We're at an immature stage in the development of cloud computing. Today, the cloud represents the exception to way organizations manage technology. As the decade progresses, cloud computing will mature and evolve into the core of all IT systems.
1. Independent Clouds
Most organizations today that use cloud computing (and most are using the cloud in some form) are at this level. These organizations leverage cloud services with little or no interoperation between those cloud systems. Perhaps they are just using one cloud service or they are using multiple, distinct services like SalesForce.com for CRM and The Rackspace Cloud for Infrastructure.
2. Cross-Cloud Failover/Disaster Recovery
The easiest path to a multi-cloud world is leveraging one cloud for disaster recovery for another cloud. It's not simply backing up data into the cloud; it's building out a reliable mechanism for executing a DR plan in one cloud for operations running in another.
3. Specialized clouds
Specialized clouds could also be called interdependent clouds. At this level, one cloud performs one function that may have dependencies on services from another cloud. For sound operation under the model, you must have solid processes and management systems in place to coordinate the cross-cloud dependencies. Operationally, a failure in one cloud results in downtime for the full solution.
4. Cloud Bursting
Cloud bursting involves the movement of workloads from one cloud to another as demand exceeds the capacity of the original cloud. As with dependent operation, the overall solution can fail in the event the main cloud fails. Cloud bursting, however, can tolerate the failure of the bursting clouds.
5. The Cloud of Clouds
The most sophisticated level of cloud computing is where your organization has weaved multiple clouds into a single abstract cloud capable of tolerating the failure of its components clouds. From an operational perspective, the cloud of clouds appears as a single, unified cloud. The heterogeneity is hidden from you and enables more efficient cloud operations.