Cloud Computing Models

• A true cloud has all five NIST essential characteristics
• On-demand self-service means provisioning with no human help
• Broad network access serves any standard client over the network
• Resource pooling is multi-tenancy: one shared pool serves many customers
• Elasticity scales out and back in automatically; scalability only adds
• Measured service meters usage so cloud can bill pay-as-you-go
• IaaS rents raw infrastructure and leaves the OS to you
• PaaS runs the OS and runtime; you deploy only your app
• SaaS delivers a finished app; you manage only settings and data
• IaaS to PaaS to SaaS, the provider owns more of the stack
• DaaS delivers a whole desktop the way SaaS delivers an app
• On-premises VDI runs on your servers; DaaS runs on the provider's
• Public cloud is open to the general public on shared infrastructure
• Private cloud means dedicated to one org, not necessarily on-premises
• Community cloud is shared by organizations with a common concern
• Hybrid cloud binds two or more distinct clouds so workloads move
• Deployment model and service model are independent choices
• High availability is about staying up, not about handling load
• File synchronization keeps files identical across a user's devices
• Shared resources are internal in a private pool, external in a public one
• Non-persistent VDI hands out a fresh pooled desktop each login and discards changes at logout
• A thin client is a minimal endpoint that offloads its computing to a central server
• A lost thin client exposes no data because VDI keeps everything on the server

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