You know you want to move to the cloud, but you don’t know which of the three major options – public, private and hybrid – are right for you. We’re here to help with this quick overview of the options, as well as the pros and cons of each.
Think of this as a server in the sky. Public cloud, also known as infrastructure-as-a-service, provides the equivalent of a data center in a highly scalable, virtualized environment accessed over the internet. Customers can provision virtual servers – called “instances” – and pay only for the capacity they use. Many public cloud features are automated for self-service. Users can deploy their own servers when they wish and without IT’s involvement. Accounting and chargeback are automated. In fact, organizations often find the public cloud delivers the most significant savings not in equipment costs, but in administrative overhead.
The best applications to deploy in a public cloud are those that are already virtualized or that run on unmodified Linux or Windows operating systems. Commercial, off-the-shelf applications are a good example. Public cloud is also a good platform to use in evaluating and testing new applications, since many public cloud providers offer a wide variety of applications on a pay-as-you-go basis. Public cloud is also well suited to developing so-called “cloud native” applications, such as mobile apps.
Public cloud isn’t ideal for every use. Homegrown applications on legacy platforms or those with significant interdependencies may not migrate smoothly. Organizations that aren’t careful to manage instances can can end up paying for unused capacity. There are also hidden costs to be aware of, such as surcharges for data uploads and downloads or upcharges for guaranteed levels of service. Regulatory issues may also limit the use of public cloud for some applications entirely.Private Cloud
This is essentially a public cloud for use only by a single customer. Private clouds may be constructed on premises using virtualization and automation software, or licensed from service providers who deliver cloud services either from their own data centers or even on the customer’s own premises.
Private cloud is popular with companies that need tight control over data, whether for security, privacy or regulatory purposes. In regulated industries that specify how customer data must be stored and managed, it is sometimes the only cloud option. It’s also attractive for companies that need guaranteed service levels without the unpredictability of the public internet. Finally, private cloud provides the highest level of control for organizations that want deep visibility into who is using resources and how.
Private cloud is typically more expensive than public cloud because service providers must allocate capacity exclusively to the dedicated environment. However, that isn’t always the case. For companies with large capital investments in existing infrastructure, an on-premises private cloud is a good way to add flexibility, automation and self provisioning while preserving the value of their existing equipment. For predictable workloads, it can be the cheapest of the three models.
This is the most popular option for large corporations, and is expected to dominate the cloud landscape for the foreseeable future. Hybrid cloud combines elements of both public and private cloud in a way that enables organizations to shift workloads flexibly while keeping tight control over their most important assets. Companies typically move functions that are handled more efficiently to the public cloud but keep others in-house. The public cloud may act as an extension of an on-premises data center or be dedicated to specific uses, such as application development. For example, a mobile app developed in the public cloud may draw data from data stores in a private cloud.
Many of the benefits of hybrid cloud are the same as those of private cloud: control, security, privacy and guaranteed service levels. Organizations can keep their most sensitive data on premises but shift some of it to the public cloud at lower costs. They can also reduce costs by using public cloud to handle occasional spikes in activity that overtax their own infrastructure, a tactic known as “cloud bursting.” Hybrid cloud is also a transition stage that companies use as they move from on-premises to public cloud infrastructure.
There are many more dimensions to the public/private/hybrid cloud decision. A good managed service provider can help you understand the options and estimate the benefits and trade-offs.