In public clouds the cloud resources (like servers and storage) are owned and operated by a third-party cloud service provider and delivered over the Internet. With a public cloud, all hardware, software and other supporting infrastructure is owned and managed by the cloud provider. In a public cloud, you share the same hardware, storage and network devices with other organizations or cloud “tenants”.
High scalability/agility – you don’t have to buy a new server in order to scale
Pay-as-you-go pricing – you pay only for what you use, no CapEx costs
You’re not responsible for maintenance or updates of the hardware
Minimal technical knowledge to set up and use - you can leverage the skills and expertise of the cloud provider to ensure workloads are secure, safe, and highly available
There may be specific security requirements that cannot be met by using public cloud
There may be government policies, industry standards, or legal requirements which public clouds cannot meet
You don’t own the hardware or services and cannot manage them as you may want to
Unique business requirements, such as having to maintain a legacy application might be hard to meet
What is a private cloud?
A private cloud consists of computing resources used exclusively by one business or organization. The private cloud can be physically located at your organization’s on-site datacenter or it can be hosted by a third-party service provider. But in a private cloud, the services and infrastructure are always maintained on a private network and the hardware and software are dedicated solely to your organization.
You can ensure the configuration can support any scenario or legacy application
You have control (and responsibility) over security
Private clouds can meet strict security, compliance, or legal requirements
You have some initial CapEx costs and must purchase the hardware for startup and maintenance
Owning the equipment limits the agility - to scale you must buy, install, and setup new hardware
Private clouds require IT skills and expertise that’s hard to come by
What is a hybrid cloud?
In a hybrid cloud, data and applications can move between private and public clouds for greater flexibility and more deployment options. For instance, you can use the public cloud for high-volume, lower-security needs such as web-based email and the private cloud (or other on-premises infrastructure) for sensitive, business-critical operations like financial reporting.
You can keep any systems running and accessible that use out-of-date hardware or an out-of-date operating system
You have flexibility with what you run locally versus in the cloud
You can take advantage of economies of scale from public cloud providers for services and resources where it’s cheaper, and then supplement with your own equipment when it’s not
You can use your own equipment to meet security, compliance, or legacy scenarios where you need to completely control the environment
It can be more expensive than selecting one deployment model since it involves some CapEx cost up front