Special Feature
Part of a ZDNet Special Feature: Integrating the Hybrid Cloud

Weighing the pros and cons of public versus hybrid clouds

Should you use public cloud exclusively or take a combined approach, with some of your data hosted internally? Here's a look at the good and the bad.

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Image: iStock

Hybrid clouds combine public and private clouds with an on-premises data center solution. But a lot of factors go into deciding whether public or hybrid cloud is best for your organization. Let's take a look at the advantages and disadvantages of the two models.

The public cloud value proposition

A public cloud is an internet-accessible data center run by a third-party provider that hosts the applications and data of multiple companies. Public clouds keep the applications and data of each company separate from those of other companies by offering multi-tenant services. Each tenant (company) that uses the cloud has a software-defined partition that keeps its applications and data separate from the other tenants.

The value of the public cloud for most companies is based on perceived cost savings and faster deployment of key applications that the public cloud provider can get up and running quickly.

For instance, if you have a public cloud that supports the virtual implementation of all your office software, you can avoid the task of having to purchase and install multiple individual computer software licenses for word processing, spreadsheets, and other office applications -- and you escape the effort and expense of upgrading and/or replacing desktop and laptop computers that are needed if you physically host this software. Instead, you simply run all the office applications on a public cloud that already has the software, the infrastructure to run it, and the support staff to ensure that the applications stay running.

In addition, since the software is hosted in the cloud, you don't need to purchase and keep track of individual per-machine software installations and licenses. You can even downsize your hardware purchases because most of your employees will need only inexpensive thin client desktops and laptops without hard drives.

This cost and labor savings argument is what often drives businesses to use a public cloud solution -- and the value proposition can be extended to other types of applications that also run on public clouds, including project collaboration and management software and cloud-based versions of common business systems, like HR, sales, marketing, and ERP.

If you're a small business with limited IT staff, you can take advantage of the public cloud provider's support staff, which can maintain your applications for you. All your employees need to do is log into a cloud access portal -- and all your IT staff needs is a telephone or email contact with the vendor for purposes of problem resolution. In fact, the public cloud business case can be so compelling that a small organization that can't afford its own IT could potentially host all its applications on a public cloud. The cloud services would be paid for on a monthly subscription basis, and aside from investing in some thin-client workstations and an internet connection, the company would be saved the expense of investing in its own hardware, software, and data center.

The disadvantages of a public cloud solution

Many companies shy away from public cloud because they fear losing control of IT applications and data. A company can feel powerless if it's running mission-critical applications on a public cloud service. What if an unexpected outage in the cloud occurs?

SEE: Ask potential cloud vendors these 10 security questions (TechRepublic)

The confidentiality and privacy of the data that companies store in a public cloud are also concerns, especially when you're promising your customers that you will protect this data. Closely connected with the data protection issue is security. Many companies today do not have full visibility of security in a public cloud, so they can't be sure that the security exercised in the cloud meets or exceeds the security requirements they maintain in their own companies. The bottom line is that there is considerable anxiety in companies over the safety, confidentiality, and security of their applications and data in a public cloud where they are assigning responsibilities for these assets to a third-party provider.

The hybrid cloud value proposition

An alternative to the exclusive use of public clouds is the hybrid cloud -- so named because it's a combination of IT that uses not only public clouds, but private clouds and an on-premises data center as well.

SEE: The state of cloud computing: 10 things you need to know (TechRepublic)

The advantage of a hybrid approach that includes your own data center is that it gives you maximum flexibility to determine where your IT applications and data are hosted. For example, you might choose to place all your office applications and data in a public cloud so you can use thin client computing internally and avoid installing and purchasing separate software licenses. At the same time, you might decide it's too risky to place your mission-critical ERP system in a public cloud. So you might opt to keep the ERP system on premises in your own data center, where internal IT staff is responsible for it.

If you've virtualized all the servers and data storage in your data center, you have the flexibility to move mission-critical applications like ERP to the private cloud. In that scenario, your users can sign in to a system access portal, much as they would if they were accessing a public cloud service -- only the cloud they'll be accessing is inside your company's own network, run by corporate IT as a private, company-owned cloud service.

Another variety of private cloud is where a company subscribes to an outside cloud service. The cloud service provider agrees to run only the company's applications on a dedicated cloud, which no other company has access to. In either scenario, IT gets peace of mind because it can administer, monitor, and secure its own applications and data with full access and visibility.

The disadvantages of a hybrid cloud solution

Despite the benefits of moving to a hybrid cloud IT architecture that combines public and private cloud with on-premises IT in the data center, there are some disadvantages. For one thing, IT infrastructure management becomes more complex. Secure data connections need be made between all the on- and off-premises IT destinations -- and your own IT staff will often be faced with having to integrate these application and data resources so they can readily exchange data as needed.

A hybrid cloud solution is also costlier than a public cloud alternative that is paid for on demand or by subscription. With a hybrid cloud, you are still making hard dollar investments in your own data center. If you're using private as well as public clouds, the costs to create and maintain private clouds are higher.

SEE: Cloud security: 10 things you need to know (TechRepublic)

Industry trends

Research shows that 70 percent of companies are implementing and/or considering implementing a hybrid cloud approach to IT. That approach offers flexibility to take advantage of cost savings at the same time that companies meet their compliance, security, and data safekeeping obligations.

In deploying this hybrid cloud approach, company trends are to:

  • Deploy non-mission-critical applications, like document management and archiving, office applications, and application development and testing to public clouds.
  • Maintain mission-critical applications and data either on premises in their data centers or on a private cloud that is usually created and run by the company and that exists inside the corporate network firewall.

Increasingly, companies are also embracing public cloud providers who offer their services as a SaaS (software as a service). With SaaS, a company gains access to important applications and can take advantage of the expertise of the SaaS vendor's staff and consultants. This is especially useful when the company has limited internal expertise (an HR talent management system is a good example) and can profit from the vendor's specialized expertise and know-how.

There is no single best-practice approach to the cloud for companies. However, it's becoming increasingly clear that a hybrid approach to the cloud and the data center presents the most deployment and cost options -- and it's hard to argue against the flexibility that this approach offers.

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