“Hybrid Cloud” – In a Class By Itself

You’ve probably read the NIST’s definitions of Cloud Deployment Models, including their definition of hybrid cloud. If not, here’s a refresher:

Hybrid cloud. The cloud infrastructure is a composition of two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).

I’ve already commented on the ambiguity surrounding the meaning of private and public cloud. (Although the NIST is fairly clear about them, meanings have eroded through general misuse, much as premise has sadly become acceptably synonymous with premises.) Hybrid, I’m afraid, has its own issues, primarily because it is in the same list with public and private. Of the four, only hybrid is defined in terms of the others. (“Baaaaad NIST!”)

Hybrid isn’t a kind of cloud deployment. It is an advanced form of coordinating multiple deployments, regardless of their specific individual attributes.  As such, it probably belongs in a category all its own, distinct from the three individual types of clouds NIST has identified. The industry is hung up on private-to-public hybrid scenarios, most likely due to the cloud bursting scenario which epitomizes hybrid deployments for so many.  But, according to NIST, if I’m using two public clouds together, that’s hybrid.  If I’m using my private cloud in conjunction with someone else’s, that’s hybrid.  Wherever two or more distinct clouds are used in composition, there also is hybrid.

(An aside: The degree of integration required between the two-or-more clouds to qualify together as a hybrid cloud is either “proprietary or standardized.”  That’s pretty ambiguous, too.  I suspect screen-scraping qualifies as “proprietary” so I believe nearly everyone is “doing hybrid” to some extent today, whether they know it or not.)

So me must stop thinking of hybrid cloud as something sitting on the same shelf with public and private – it’s is much more than “just another cloud deployment model.” It transcends those concepts. We must also stop thinking of it as “coming in the future” – it is already here, and continues to mature in degree of integration and ease of use with each passing day.

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Is “Cloud Bursting” a Reasonable Scenario for Hybrid IaaS?

When people list use cases for “hybrid cloud computing” the “cloud bursting” scenario is nearly always trotted out first.  But is bursting really so desirable?  Here’s my answer first, followed by the explanation:

  • For IaaS? NO
  • For PaaS? YES

I think bursting gets prime-time coverage because it represents perhaps the most disruptive use case for hybrid cloud computing – the ability to augment your own data center’s compute power by harnessing other capacity (public cloud, other private clouds, etc.). But the devil is in the details, and an explanation of how that augmentation is actually achieved is usually a hand-waving exercise.

Since we’re probably talking IaaS deployments, then a brute force method of achieving cloud bursting would be migrating “workloads” between cloud hosting targets – something similar to cold migration of VMs between hypervisor hosts.  But migration across WAN links, as would be probable in this bursting scenario, is vastly different from the relatively lightning-fast migration (cold, warm, or live) available with, say, an ESX cluster. Clearly, some form of optimization is required.

And then we start talking about compression and de-duplication and WAN optimization – all of which try to mitigate the real underlying problem: IaaS-type VMs are simply not the right choice of container to achieve truly scalable and efficient bursting solutions. I contend the ultimate “optimization” for workloads that will enable them to move at will between cloud hosting targets is the “PaaS-ification” of them.

To take full advantage of the hybrid model, applications must be designed with that model in mind.  Distributed execution and data access are more recent tenets in programming, requiring more thought and planning.  Most applications in private data centers are born of simpler, but less flexible architectures.  To their credit, IaaS-type VM’s are an effective way to salvage legacy applications in the early years of the cloud revolution.  But they’re inefficient, blunt instruments for achieving cloud bursting.  Yes, cloud bursting for IaaS will be implemented, but it will have limited value and eventually be eclipsed by more PaaS-like implementations. No application will fully realize the benefits of hybrid cloud deployments – bursting included – until it has been re-written specifically to take advantage of it.


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Public/Private Cloud? Not really…

I’ve been hearing it more and more.  The labels “public” and “private” are losing their effectiveness in the circles of cloud computing researchers.  These words are ambiguous to the point they typically must be accompanied by clarifying phrases to help make their meaning clear.  Does “private” mean 1) on-premises? 2) owned by the user? 3) single-tenant?  And does “public” mean 1) off-premises? 2) not owned by the user? 3) multi-tenant? Cases could be made for off-premises single-tenant clouds that are owned, but not necessarily managed, by the user.  What are they? Public? Private? Something else?

And don’t even get me started on “hybrid…”

Ultimately, I think what has in the past been poorly conveyed by “public” and “private” adjectives are in the future going to be explicitly defined by four attributes:

  1. Proximity – Is it on or off premises?
  2. Ownership – Does the user own it, or do they pay for it as a service?
  3. Management – Does the user manage it, or pay someone else to do so?
  4. Tenancy – Does the user share it with others, or have it to themselves?

Before you dismiss some combinations as unlikely or even impossible, consider that things like a user-owned off-premises outsourced-managed multi-tenant cloud could certainly be built, and may even have use cases not yet considered.  The important thing is that as technologies for cloud computing evolve, that they do not preclude creating such things if the need arises.

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I’ve finally gotten around to getting more serious about my blogging.  Although this site is a general purpose “personal” web site, the front page is going to be focused on cloud computing technologies and my own personal thoughts about that space. Look for new posts, and an updated WordPress theme soon.

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