Q&A: Understanding Private vs. Public Clouds

The president and COO of a managed services firm that offers private cloud computing explains the differences between public and private cloud computing and what each is best suited for.

• By Linda Briggs
• 12/16/2009

One way to sort out clouding computing offerings is whether the provider works within a public or a private cloud. To help untangle the differences, we spoke with Kenneth Ziegler, president and chief operating officer of Logicworks, a managed services hosting provider specializing in complex architectures and high-availability solutions.

Ziegler explains the difference as he sees it between public and private clouds; he notes that the technology of cloud computing can offer advantages to most -- if not all -- businesses. The key is knowing what you want and need. “Regardless of your [company’s] background,” Ziegler says, “there is a cloud provider out there that’s a good fit. Contrary to popular belief, however, there is no ‘one-cloud-fits-all’ solution.”

BI This Week: How do you define “the cloud,” especially as it relates to BI? Is the cloud the same as “managed hosting” or “platform-as-a-service” or some of the many other terms currently being tossed about?

Kenneth Ziegler: In my definition, the cloud is any technology or combination of technologies that resides at and is managed by a service provider, leading to greater efficiencies in the delivery of IT. In the case of BI, it could take the form of a SaaS [software-as-a-service] product in which an internal team explores data with a browser, or it could be a custom BI or data warehousing application that requires its own infrastructure.

Here’s what is key about cloud computing: Rather than worrying about the IT operations functions, that portion is left to an infrastructure service provider, allowing you to focus on analytics and results rather than hardware, operating systems, security, scaling, compliance, and so on.

The cloud category in which we participate at Logicworks is “infrastructure-as-a-service” (IaaS), and our specific offering is known as Private Cloud Hosting, which combines the efficiencies and benefits of complex managed hosting with virtualization and automation.

What are some prime advantages of cloud computing?

The prime advantages of cloud computing in the broadest sense (that is, as applied to all “X-as-a-service” providers) are almost identical to those of IT hosting. They include:

1. You incur no capital expense. This is a huge advantage when access to credit isn’t easy and CFOs are getting involved in IT delivery decisions.
2. It puts an end to multi-vendor management for hardware, operating system software, bandwidth, power, cooling, and the data center, since these requirements are all included with the service.
3. The cloud offers “pay-as-you-grow” scalability. You pay only for what your application needs as it needs it, rather than over-investing in infrastructure.
4. Businesses see faster time-to-market. Providers keep resources available on demand, which drastically reduces the lead time for a client application to “go live.”
5. The cloud offers labor efficiency. There’s no need to hire a 24x7 team to perform break/fix on your infrastructure.
6. Hardware, and hardware lifecycle management, are no longer concerns.

Can you explain how the concept of a private cloud differs from a public cloud, and some of the pluses and minuses of a private cloud?

The public cloud is typically used for processing (that is, compute) power or shared storage delivered to a client on a “pay-by-the-sip” basis (often dollars per CPU hour or dollars per GB of storage). That power is delivered via virtualized slices of a server within a large grid of physical servers and storage, all residing on the premises of a Web services provider.

Hosted private clouds include “shared-nothing” architectures, which are custom designed for enterprise clients who have specific performance, compliance, and scalability requirements. It is delivered in “pay-by-the-glass” increments, requiring a minimum high-availability configuration, with clients adding their own virtual machines as they grow, all fully managed by the service provider.

With private cloud hosting, you get in-depth access to engineering expertise, specifically around operating system and database high availability, and virtual machine administration, providing a level of labor efficiency that simply isn’t available in the public cloud universe. Private cloud hosting provides a level of IT operations integration that cannot be achieved via public clouds. This integration gives enterprises the assurances they need in order to trust their most critical applications to outside parties.

Private clouds should be deployed for applications and content that require performance, compliance, security, and committed resources. The same way high-performance, steady-state applications don’t make sense in the public cloud, static, non-transactional data makes little sense in the private cloud. Likewise, for developers just getting started on an application, the minimum fees associated with private clouds can be prohibitive, which is why a pay-by-the-sip public cloud service is probably a better fit for anyone in the proof-of-concept phase of a business or application.

Regardless of whether it’s a public or a private cloud, what are some of the things that users should be aware of with cloud computing?

The answer greatly depends on the provider and type of service the client is seeking. In almost all cases, there is little to no customer support within the public cloud. There are also security concerns, both in terms of remote exploits and group-policy management options (or lack thereof).

Current public cloud offerings aren’t designed for steady-state applications. In fact, high base-load applications can actually be more expensive to run in the public cloud. This is because in most cases, public cloud providers statistically multiplex (in other words, potentially oversubscribe) their load capacities. Therefore, companies using highly transactional databases or high-performance applications turn to bare-metal or private cloud hosting, or a hybrid model of public front-end and private or bare metal backend architectures.

Some applications simply run better on bare-metal infrastructures, but it doesn’t mean that each tier of a system’s architecture needs to run on bare metal to be most efficient. Clients can run their Web services in the public cloud and load-balance their traffic across several virtual instances, but keep the transactional parts of their system running on their own dedicated equipment.

When a data warehouse or data mart is located “in the cloud,” where does any analytical processing take place? Is data transferred to and from the cloud for analytics?

Cloud hosting platforms are simply new combinations of technologies that allow clients to deliver the same applications as previously, only more efficiently, by using virtualization and automation maintained by the service provider. Data is still processed on servers, only not client-owned servers running internally. Typically, the data is transferred back and forth via the Internet, most likely via a VPN or other secure tunnel.

With cloud computing, specific to data warehouses or BI applications, how are service level agreement (SLA) issues such as uptime, disaster recovery, and query response time handled? Are there industry best practices available yet?

Cloud providers, most of whom were previously or still are leading managed hosting providers, are highly motivated to keep their architectures up and running as close to 100 percent of the time as possible. A good provider will design full fault-tolerant architectures with no single point of failure -- from the firewalls, switches, and load-balancers, all the way down to the database architecture and storage arrays. Businesses running BI or maintaining critical data of any kind are the most sensitive to data loss and downtime, and will choose the providers with the appropriate controls and procedures in place to maintain critical systems.

Diligence should include requiring that a provider has completed an SAS70 Type II audit, ensuring that their cloud infrastructure is in best-in-class data center facilities, reviewing disaster recovery plans, client references, and examining the provider’s history and experience managing clients with similar needs.

What does the provider’s average client look like? Do they have a slice or two in the cloud, or two to three dedicated servers, or do they have multi-tier architectures with performance and compliance requirements, critical content, and custom IT operating requirements? Regardless of your background, there is a provider out there that’s a good fit, but contrary to popular belief, there is no “one-cloud-fits-all” solution.

Ultimately, you will benefit by being able to pick and choose the right combination of cloud, bare-metal, and in-house solutions to satisfy their specific IT needs more efficiently than ever before.

What does Logicworks bring to table regarding cloud computing?

Logicworks provides fully managed private cloud hosting, which includes the system and database management expertise and customization associated with complex managed hosting, but also adds the benefits of automation and virtualization. Typical clients are SaaS providers, major media companies, and online retailers. Clients incur no capital expenses and work with Logicworks to design solutions to meet their current requirements, paying only for what they need as they need it, with on-demand scalability as they grow. Logicworks offers a full suite of cloud design and migration services to allow clients to immediately begin taking advantages of the IT delivery efficiencies that cloud computing provides.