Private Cloud or Public Cloud?

 

I’ll be very clear up front… I am not a big believer in private cloud (versus public cloud) for most organizations and use cases. But in the spirit of objectivity, let’s look at both approaches and when one makes more sense over the other. I reserve the right to offer my biased but carefully thought out perspective along the way, because well, this is my column after all!
 

Let’s start at the beginning…
 

Private cloud, unlike public cloud, begins with dedicated infrastructure. Customers leveraging private cloud enjoy the benefits of not having to compete with other “tenants” for resources. The flip side of this (among many other issues) is that capacity is fixed, until it’s explicitly increased, but more on that later.

In theory, private cloud is also more secure than public cloud precisely because there is no resource sharing between tenants. In reality, public cloud providers generally do a great job at addressing security and tenant isolation, both when data is resting as well as when it’s processing or moving. But in some cases there are strict regulatory and compliance guidelines that explicitly demand separate infrastructure, which private cloud addresses well.
 

Here’s what private cloud is not (necessarily):

What’s wrong with any of the 3 points above? Absolutely nothing – and in fact, these mechanisms actually cover what most organizations really need. Layering the complexity of cloud on top of that doesn’t necessarily make sense, unless:

I’ll argue that the fourth bullet is the most important, because I believe all organizations should be looking at a public cloud strategy. Owning (or outsourcing) dedicated infrastructure is prohibitively expensive for the elastic usage patterns we see across all industries today. Unless there is a compliance/regulatory reason not to, it’s time to at least start thinking about a migration strategy – certainly ahead of any further investment in dedicated resources. Hybrid cloud (bursting to public for more capacity/new applications) is an interesting alternative, but this demands migrating legacy infrastructure to cloud mechanisms anyway. Otherwise you are not bursting, you are simply using public cloud as a new pool of resources – which is fine too, but let’s call a spade a spade!
 

Assuming private cloud is right for your organization, consider some basic deployment requirements and their associated costs:

One other very key factor to consider with private cloud is that you must build it from the infrastructure up. Whether you own the resources, or you outsource them (e.g. to a service provider). This means you are starting with compute, storage, and network – also known as IaaS (Infrastructure as a Service). In the public cloud space, you have the choice of immediately available higher classes of service to solve problems more effectively – e.g. SaaS and PaaS. While you can eventually get there with private cloud, you must build the underpinnings. For a refresher, read “Choosing the Right Class of Public Cloud Service”, and think about how to address this with your private cloud implementation. You don’t just want to hand out IaaS to all your end users, as this can be disastrous in terms of productivity and even adoption.
 

Hyper Converged Infrastructure (HCI) is a relatively new trend aimed specifically at mid-sized companies looking to implement private clouds (or turn-key dedicated resource pools). These solutions combine storage, networking, and compute into a vertically integrated, horizontally scaling appliance model. Obviously this doesn’t always mean “best of breed” for all capabilities, but at least it eliminates much of the initial build complexity. If your organization needs to add new infrastructure to implement private cloud, this is a good solution space to look at. Again, expect to navigate some confusing vendor waters and cut through a lot of hype, but trust that the “sticker shock” pales in comparison to what it would cost you to build that all from scratch. (CRN has a good introductory overview of 13 Hyper Converged Infrastructure solutions.)
 

Of course, if you don’t really need private cloud, just start consuming public cloud with no up-front investment! Which brings us to…
 

Assuming you are not able to reuse a lot of infrastructure and software for your private cloud implementation, and you have no compelling reason to use private cloud (such as regulatory/compliance pressures), then I’ll argue public cloud almost always makes more sense. This also assumes that your use cases actually benefit from cloud more than from “reserved”, or “dedicated” infrastructure – that is, they are very dynamic/on-demand in nature versus static and predictable. Remember that cloud is not the most cost-effective way to operate steady, predictable workloads. In fact it exists for quite the opposite reason. So, assuming that your use cases are actually a good fit for cloud in the first place, consider the following:

What you end up doing largely depends on how far along into your cloud journey your organization already is. If you are just now looking to take that first step, and the arguments for private cloud include things like control and security, I urge you to think about how much better your organization can do than established multi-billion dollar practices like Amazon Web Services, Microsoft and Google, or mature, focused solutions such as Salesforce.com and Nimbix. Don’t let ego and the NIH (“not invented here”) mentality make the huge investment of your cloud migration even more nebulous (pun intended)!