Public, Private, Hybrid: What’s the Difference?
A public cloud refers to a service that offers applications and IT functions to a general customer base with very few opportunities for individualization. However, agency officials often define a public cloud as one that is hosted off premises by a third-party provider, but is protected in the sense that it is governed by a negotiated contract and includes customized pricing, service and security levels, as well as a strategy for data return should the arrangement end.
- Pros: No capital investment; access to economies of scale and specialized knowledge; predictable pay-as-you-go costs
- Cons: Loss of control over agency data; less ability to customize and prioritize how resources are managed
- Popular uses: E-mail, storage, standard productivity software, non-core applications
A private cloud is created for and used expressly by an individual agency.
- Pros: Control of data location, resource provisioning, security, service levels and compliance measures; gain flexibility and remote access
- Cons: Resource-intensive and expensive; requires specialized IT expertise
- Popular uses: E-mail, enterprise resource planning, human resources and finance systems
A hybrid cloud typically comes in two flavors: a cloud run by agency for use by a group agencies; and an arrangement in which the underlying infrastructure or all or part of the application is hosted offsite by a public cloud provider, but more sensitive components, and sometimes the application itself, are maintained within a private cloud by the institution.
- Pros: Speed to market; access to specialized application knowledge and high-capacity IT resources
- Cons: Loss of control
- Popular uses: ERP, high-performance computing, massive data storage and management
