Public cloud vs. private cloud (and also hybrid cloud)
Cloud is an obvious choice for modern organizations looking to scale their computing capabilities. Less obvious is which type of cloud: public, private, or hybrid. Here’s a quick comparison of the benefits, drawbacks, and situational considerations of each cloud computing environment.
A public cloud is perhaps the simplest of all cloud deployments. A cloud provider distributes computing resources, services, and platforms—developed from hardware owned and managed by the cloud provider—to multiple clients over a network. Public clouds always have a multitenant architecture, which means multiple virtual instances exist on a single software instance. Each tenant (also known as a client) comprises a group of users who share common access with specific privileges to the software instance. The clients don’t own the gigabytes of storage their data is backed up to; don’t manage operations at the server farm where the hardware lives; and don’t determine how their cloud-based platforms, applications, or services are secured or maintained. A client needing more computing resources simply pays the public cloud vendor by the hour or byte to have access to what’s needed when it’s needed.
Public cloud providers have extensive networks that afford their clients (theoretically) unlimited access to resources. You pay as you go and can scale out quickly if you need additional resources. Upfront costs are usually low since you’re not investing in the actual hardware. Operational costs may be less predictable though if you have unanticipated spikes in use. But that’s a benefit of public cloud; you pay for more computing power only when you need it.
Sharing resources with others does come with downsides. Multitenant environments tend to have more security threats and sensitive workloads that require isolation may not be compliant on a public cloud. That’s why it’s important to know what you’re responsible for and distribute workloads accordingly.
Private clouds are similar to public clouds except that the systems are dedicated to a single client with isolated access. Like public clouds, private clouds are delivered via self-service environments (sometimes over the internet), but are secured by a private network, privacy settings, or management. Private clouds offer a flexible, customizable environment for running your specific workloads—nice for business legacy apps that may not function in a public cloud.
Private clouds excel at capacity efficiency when compared to dedicated virtual servers (which are not clouds), but can’t match the infinite resources of public cloud. Private cloud owners can get more cloud resources if needed, but it means you have to buy new hardware (on-premise), or rent additional private infrastructure from a vendor (off-premise)—both of which take longer and cost more than using a public cloud.
A dedicated cloud is a special kind of private cloud within another cloud. You can have a dedicated cloud on a public cloud (e.g. Red Hat® OpenShift Dedicated) or on a private cloud. For example, the accounting department of an organization could have its own dedicated cloud within the organization's private cloud.
Hybrid clouds enjoy the best of public and private clouds. A hybrid cloud is a combination of 1 or more public and private clouds orchestrated by management and automation software that allow workloads, resources, platforms, and applications to migrate between environments. On-premise infrastructure, traditional virtualization, bare-metal servers, and containers can be incorporated, but it must be added alongside the public and private clouds. Without the clouds, it’s just a hybrid environment—not a hybrid cloud.
In hybrid cloud, separate cloud environments may remain unique entities but have the potential for connections, integration, and portability across those clouds. This separate—yet connected—architecture is what allows enterprises to run workloads in the most efficient cloud deployment: critical workloads in the private cloud, less sensitive workloads in the public cloud, and pull resources from each environment as desired. For example, connecting your private cloud to a public cloud can help you scale out during peak periods or predictable outages by “bursting” workloads into the public cloud. You can scale up by adding virtualization to the set and scale out with the best cloud for the situation. Hybrid clouds are all about choice, but that ability to choose is only as flexible as the integration and automation systems that unite them.
Choosing the right cloud
Choosing a cloud depends on your particular circumstance*. Here are some of the things to consider in relation to what public, private, and hybrid clouds are good for:
- Types of applications and their current and predicted use
- Compliance and regulations that affect your workloads
- Technical knowledge of your staff
- Business goals
- Legacy workload interoperability
- Disaster recovery plans
- Integration strategies
Public clouds are good for:
- Workloads with high volume or fluctuating demands.
- Non-sensitive data and lower-security workloads.
- Some public-facing operations.
- Long-term storage or data archive.
- Collaborative projects.
Private clouds are good for:
- Workloads with predictable usage patterns.
- Sensitive workloads with strict security and privacy regulations.
- Mid to large-sized organizations that need and can afford enhanced control.
- Legacy applications that don’t work in a public cloud.
Hybrid clouds are good for:
- Everything that private and public clouds are good for.
- Organizations that need the operational flexibility of the public cloud and the privacy of a private environment and can adequately support the management of a hybrid environment.
Why Red Hat?
You want to deploy some type of cloud to improve your business—but if you’re looking at the difference between the 3 cloud deployments, it’s likely you’re having trouble figuring out where to start. But don’t worry: Everyone started where you are right now. We not only help you get to the cloud—we can help you be productive in the cloud. Our open source technologies bring a consistent foundation to any cloud deployment: public, private, hybrid, or multi. With a standard operating system that works the same in any environment, a container platform that packages and moves apps from cloud-to-cloud, and tools that help you manage and automate it all, we give you the portability needed to succeed on more than 600 certified public cloud platforms and the products to deploy your own private cloud.
Is your cloud strategy limited by your infrastructure?
Some virtual infrastructures restrict your software choices by binding you to increasingly expensive enterprise-license agreements. Migrating to open source virtualization could open your path to the cloud.
We can help you build a secure cloud
Everything you need to build and deploy a secure private cloud, including an operating system that integrates Security-Enhanced Linux (SELinux) and a virtualization platform that incorporates sVirt.
A management and operations platform that unifies hybrid cloud environments, so you have access to which users have what specific privileges at all times.