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How to choose between IaaS and SaaS cloud models

Even if you already moved a few workloads to the cloud, it's never too early to start looking at where you are going and never too late to make a change. See if IaaS or SaaS is the right service model for your organization.

Once you decide to move to the cloud, the next step is determining which service model fits your needs. The choice largely depends on how much control your organization wants over its cloud environment and applications.

There are three overarching models in cloud computing:

  • IaaS. A third-party provider supplies and maintains core infrastructure components such as servers, networking and storage. IaaS users manage and monitor the OS, data, workloads and applications. Examples include AWS and Microsoft Azure.
  • PaaS. A third-party provider delivers application development platforms and tools. The user is responsible for those environments, but the PaaS provider supplies and manages the underlying infrastructure. Examples include Google App Engine and Red Hat OpenShift.
  • SaaS. A third-party provider hosts the customer's applications. SaaS providers handle all maintenance and support, which eliminates the need for users to install and run their own infrastructure and software. Examples include Microsoft 365 and Salesforce.

We'll touch on PaaS briefly, but for the purposes of this piece, we're going to focus on IaaS and SaaS because they're the two most prominent models. They also present the biggest contrast in terms of the choices an organization must make.

Should you go with an IaaS model for more control and customization or would you rather opt for a SaaS model with its lower price tag and less management? To determine if IaaS or SaaS is the right choice, cloud architects must look at user needs and customization, while also being mindful of cost.

Prioritize the user, not cost

Too often in IT, the technology drives decisions, rather than the users. Instead, treat users' needs as the starting point for deciding between IaaS vs. SaaS.

Choose a cloud service model that puts them in the driver's seat, with guidelines and exceptions. Think of the capabilities your users might want. Even small requests, like changes to document routing flow or data entry options, can require a tremendous amount of work on the back end. If those capabilities will largely go unnoticed and unused, then SaaS is likely a better fit.

Too often in IT, the technology drives the decisions, rather than users.

Other times, that granular control is worth it, especially for IT. For example, one of the hidden challenges of using multiple cloud environments is that they all have different interfaces, which makes it difficult to get them to work together. With IaaS, you can build something unique to address this in a way that's not possible with SaaS.

Regardless, decisions about IaaS and SaaS shouldn't be limited to IT. Architects need to work with application owners, operations and end users before any cloud migration.

A move to the cloud can be held up by users demanding specialized reports and settings that, when investigated, turn out to be preferences. Have a clear picture of your organization's needs before the migration and keep communicating afterward so you're aware of any further adjustments and compromises.

Just ensure IT still has a hand on the wheel in the planning phase, or things can get out of control with too many requests and requirements. This is especially true with IaaS, which offers much more customization.

Put cost in context

Cost calculations are part of the IaaS vs. SaaS conversation, but don't let it drive the choice. Otherwise you can end up with a model that doesn't work. You'll either spend more trying to fix it, or you'll lose the money you invested if you have to go another route.

Cloud infrastructure is typically more expensive than app subscription, but it might prove to be a differentiator for your business. The amount flexibility your users need will likely help guide your decision about IaaS vs. SaaS.

Once you select your model, move to more complex tasks such as budgeting responsibilities, administrative overhead and other aspects as you prepare to move from capital expenses to operational ones. IT will have to demonstrate flexibility and evolve to handle different budget and reporting structures in the new cloud environment.

However, don't expect dramatic staffing changes. Some duties might adjust, but most of that was well on its way years ago, so cost savings by reducing personnel doesn't happen. This doesn't mean you will have more staff with IaaS over SaaS. It's an adjustment of roles and responsibilities, but that is something most IT people are used to.

Where PaaS fits in the IaaS vs. SaaS discussion

PaaS is certainly an option if you prefer a middle ground between IaaS and SaaS. It removes many of the operational burdens of IaaS while providing more flexibility than SaaS.

But it isn't a panacea, and it hasn't taken off with enterprises in the same way as the two other cloud delivery models.

That's in part because you're left in a grey area, with a foot in each side of the debate. It forces your organization into a balancing act of half measures that might not adequately address your needs. Still, it isn't wholly without merit, and there may be some that find it's their best option when IaaS and SaaS don't cut it for a particular use case.

Plan for today

When you evaluate customization options, do so based on current needs, as opposed to what you might have tomorrow. Too often, organizations get caught up with future concerns and plan for three to five years ahead. This leads to buying based on the idea that they will need some desired customization, but those customizations often never show up.

Needs constantly change, and an application stack and design often change as a result. It's not realistic to plan software consistency years in advance. You might pay more for a customization you never actually use. In this case, if your application doesn't currently require any customization, then the SaaS model would be a better, less expensive option.

However, if your IT team has a history with an application and successfully modifying it, moving to the cloud shouldn't change that. In those scenarios, IaaS is the ideal fit because it serves as a new platform to keep doing what's already working.

IaaS vs. SaaS: Use cases

Organizations will need to do their due diligence to determine which model best fits their needs. But as more workloads move to the cloud, trends regarding IaaS vs. SaaS have begun to emerge. IaaS platforms started to develop as systems from healthcare, education, accounting and HR systems move to the cloud.

Applications that are updated annually, such as HR and accounting, seem to be ahead of the curve and move quickly to SaaS-based applications. Larger-scale systems that have a bit more Unix back end, such as educational and healthcare workloads, tend to be a bit more of a challenge and often need that flexibility offered by IaaS or even PaaS.

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