Hybrid cloud is a cloud computing environment which uses a mix of on-premises, private cloud and third-party, public cloud services with orchestration between the two platforms. By allowing workloads to move between private and public clouds as computing needs and costs change, hybrid cloud gives businesses greater flexibility and more data deployment options.
For example, an enterprise can deploy an on-premises private cloud to host sensitive or critical workloads, but use a third-party public cloud provider, such as Google Compute Engine, to host less-critical resources, such as test and development workloads. To hold customer-facing archival and backup data, a hybrid cloud could also use Amazon Simple Storage Service (Amazon S3). A software layer, such as Eucalyptus, can facilitate private cloud connections to public clouds, such as Amazon Web Services (AWS).
Hybrid cloud is particularly valuable for dynamic or highly changeable workloads. For example, a transactional order entry system that experiences significant demand spikes around the holiday season is a good hybrid cloud candidate. The application could run in private cloud, but use cloud bursting to access additional computing resources from a public cloud when computing demands spike. To connect private and public cloud resources, this model requires a hybrid cloud environment.
Another hybrid cloud use case is big data processing. A company, for example, could use hybrid cloud storage to retain its accumulated business, sales, test and other data, and then run analytical queries in the public cloud, which can scale to support demanding distributed computing tasks.
Public cloud's flexibility and scalability eliminates the need for a company to make massive capital expenditures to accommodate short-term spikes in demand. The public cloud provider supplies compute resources, and the company only pays for the resources it consumes.
Despite its benefits, hybrid cloud can present technical, business and management challenges. Private cloud workloads must access and interact with public cloud providers, so hybrid cloud requires API compatibility and solid network connectivity.
For the public cloud piece of hybrid cloud, there are potential connectivity issues, SLA breaches and other possible public cloud service disruptions. To mitigate these risks, organizations can architect hybrid workloads that interoperate with multiple public cloud providers. However, this can complicate workload design and testing. In some cases, workloads slated for hybrid cloud must be redesigned to address the specific providers' APIs.
Management tools such as Egenera PAN Cloud Director, RightScale Cloud Management, CliQr's CloudCenter and Scalr Enterprise Cloud Management Platform help businesses handle workflow creation, service catalogs, billing and other tasks related to hybrid cloud.