The choice between private cloud vs. public cloud can be difficult and time-consuming; virtualization administrators must consider the impact of security, compliance, cost, scalability and hybrid cloud potential.
Consider security implications
Security is often the first reason to seek public cloud alternatives like private cloud implementations.
When an individual or business engages a public cloud, tenant workloads and data are hosted on public cloud hardware infrastructures and software stacks, which users can't see or control. The user must place complete trust in the provider to implement the physical and logical mechanisms needed to secure valued content in a multi-tenant computing environment. This ranges from physical security of servers and disks to logical systems such as configuration management, identity and access management, and logging.
Public clouds are also potentially more attractive targets for hacking, distributed denial-of-service attacks and other targeted activity intended to compromise large volumes of data rather than limiting the payoff to a single organization. When an organization needs to stay off the radar and ensure the tightest, most direct security over its environment, a private cloud might be the preferred approach.
Meet compliance demands
The choice of private cloud vs. public cloud can also be influenced by compliance demands. A public cloud typically supports compute and storage resources in numerous strategic locations across the world.
However, users typically possess limited control over exactly where data and workloads are physically located or operated. Industrial sectors subject to exacting regulatory compliance rules -- such as banking and healthcare -- might need to know or prove precisely where content is located and who accesses that content. Consequently, some industries might be unable to use public clouds for certain tasks, and might instead choose to implement a private cloud.
Mitigate cost concerns
Costs can play a significant role in the choice of private cloud vs. public cloud. A public cloud is often the most flexible cost model where users pay monthly for a la carte resources and services using some form of per-use approach.
The challenge with public cloud costs is that such a la carte offerings can quickly add up, and unpredictable or rapidly changing needs can easily result in significant unplanned costs for business users. Private clouds can offer greater levels of cost control. If the organization implements its own private cloud, the cost model is more traditional and offers the business more predictable costs than public clouds.
Estimate scalability needs
Scalability plays into the cost issue for private cloud vs. public cloud. When a business engages a public cloud, that public cloud can typically provide enormous scalability due to the provider's extensive -- often global -- investment in facilities and resources.
When a business opts to implement a private cloud, the cost and scalability of that private cloud is typically just a small fraction of comparable public clouds. However, such limitations afford the opportunity for businesses to match strategic investments in resources against their current -- and forecasted -- needs. That is, private cloud owners don't need to invest in infrastructure and resources they don't need.
Evaluate hybrid cloud potential
Scalability can also play into the potential for hybrid cloud implementations. A hybrid cloud essentially enables a private cloud to merge with one or more public cloud providers to create a seamless cloud environment. Creating a hybrid cloud requires design choices -- such as compatible APIs -- that will enable the private cloud's resources and services to be compatible with selected public clouds.
But hybrid clouds can be effective when demands for private cloud resources grow beyond that private cloud's capacity. Hybrid clouds can also be useful when deploying certain workloads or data sets that aren't constrained to a private cloud -- such as non-critical workloads or non-sensitive data.
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