Most hybrid clouds combine a public cloud with a private cloud.
What does ‘hybrid cloud’ mean?
A hybrid cloud mixes two or more types of cloud environments. Hybrid cloud deployments combine public* and private clouds**and may also include on-premise legacy infrastructure. For a cloud to be hybrid, these different environments must be tightly interconnected, functioning as one combined infrastructure. Almost all hybrid clouds include at least one public cloud.
A hybrid cloud is somewhat like a hybrid car. Hybrid cars combine two distinct technologies: an engine that burns gasoline and electric power. Each technology functions differently, and each one has its benefits and drawbacks. However, when the two are combined effectively, the result is a more efficient car than most gasoline-only cars and yet more powerful than most all-electric cars. Similarly, hybrid clouds combine the benefits of multiple cloud environments for greater efficiency and functionality.
Hybrid clouds have several uses. An organization may use its private cloud for some services and its public cloud for others, or it may use the public cloud as a backup for its private cloud. They can also use the public cloud to handle periods of high demand while keeping most operations within their private cloud.
(For more on cloud technology, see What Is the Cloud?)
What are the types of environments found in hybrid clouds?
The combination of any two of the environments listed below can be considered a “hybrid cloud”:
- Public cloud: A public cloud is a service run by an external vendor that may include servers in one or multiple data centers. Multiple organizations share public clouds. Using virtual machines, different companies may share individual servers, a situation called “multitenancy” because numerous companies rent server space within the same physical server.
- On-premise private cloud: A private cloud is a data center wholly dedicated to one company. The servers in a private cloud aren’t shared by anyone else’s software, files, or data. On-premise private clouds are maintained and secured by the organizations, not external vendors.
- Hosted private cloud: This is like an on-premise private cloud in that the servers are dedicated wholly to one organization. However, the cloud servers in a hosted private cloud are not located in an organization’s offices – instead, a third-party provider hosts and maintains the cloud servers in one or more remote data centers. The organization accesses the cloud over the Internet instead of an internal network. But unlike a public cloud, there is no multi-tenancy; the cloud servers are not shared with other organizations.
- On-premise (legacy): On-premise or legacy deployments don’t use cloud technology. Instead, organizations using this model follow the classic practice of purchasing software licenses, installing and maintaining hardware on their premises, and installing software locally on employee computers. In other words, instead of working in Google Docs (for example), employees would use Microsoft Word or some other program installed and running on their computers.
What is the difference between hybrid cloud and multi-cloud?
A multi-cloud deployment combines multiple public clouds, while a hybrid cloud combines a public cloud with another type of environment. Hybrid clouds combine apples and oranges – a multi-cloud deployment is like combining many kinds of apples.
A multi-cloud can also be a hybrid cloud if it mixes multiple types of cloud environments in addition to using multiple public clouds – just as a rectangle can be a square, but not all rectangles are squares. Conversely, a hybrid cloud deployment can be multi-cloud using several public clouds.
How do the different environments communicate with each other in a hybrid cloud?
The connection between the separate clouds is key for a hybrid cloud to work well. Public clouds, private clouds, and on-premises infrastructure can connect in a variety of ways, including:
Without a working connection between clouds, an organization is not running a hybrid cloud – they are merely running two or more separate cloud environments in parallel. They won’t reap the benefits of hybrid cloud deployments.
What are the advantages of using a hybrid cloud architecture?
- Flexibility: Hybrid clouds make switching to a different cloud deployment style easier. For instance, if a business decides to move to an exclusively public cloud deployment, it will be simpler if some business processes or storage already occur in a public cloud.
- Wider variety of technology: Via a public cloud, a business can include technology that isn’t practical to run in a private cloud, such as big data processing.
- Backups to avoid downtime: If one cloud crashes or breaks, a company can rely on the other, avoiding service interruptions. This type of redundancy is also an advantage of multi-cloud deployments.
- Meet spikes in demand: A company can run most of its processes in a private cloud and then use a public cloud for extra computing power to handle a sudden spike in workload – such as when far more users than regular access an [eCommerce site](https://www.cloudflare.com/ecommerce/) during Black Friday. This strategy is known as cloud bursting because a workload “bursts” from one cloud to a larger cloud.
- Potential cost savings: Maintaining an internal data center, such as a private cloud, can be expensive and resource-intensive. Moving some operations to a public cloud means an organization doesn’t have to maintain as much infrastructure on-premises, cutting costs.
- Keep sensitive data on-premise: Some organizations handle sensitive data, such as credit card numbers, healthcare information, or financial data. Keeping such data on-premise gives a company much more control over the security measures that guard sensitive data. In a hybrid cloud deployment, an organization can keep sensitive data in a secure private cloud and then use public clouds to run its applications.
What are the drawbacks of using a hybrid cloud architecture?
- Greater attack surface: Whenever network infrastructure becomes more complex, there is a greater chance that an attacker will find a vulnerability to exploit. A single cloud – say a private cloud – can have strong security protections in place. However, if multiple clouds from different vendors are used, not all clouds will have the same quality of security.
- More complex integrations: The connection and orchestration between different clouds are crucial. Thus, there are more steps to setting up a hybrid cloud than deploying a single public or private cloud since the connecting technology – such as a VPN – must also be set up and maintained.
- Complicated to secure: While an on-premise private cloud runs behind the company firewall, a hosted private or public cloud does not. To keep their data safe, a company may need to use multiple security products, some for their on-premises cloud and some for their public cloud. In addition, it can be tricky to validate a user’s identity across multiple clouds (access control).
