Tuesday, August 17, 2010

The Enigma of Private Cloud

If you swim in cloud computing circles you cannot escape hearing the term private cloud. Private cloud is surely the feature most in demand by the cloud computing market—yet perhaps the longest in coming, as cloud computing vendors have gone from initial resistance to the idea to coming to terms with the need for it and figuring out how to deliver it. The concept is something of a paradox, made worse by the fact that private cloud definitely means different things to different people. There are at least 5 meanings of private cloud in use out there, and none of them are similar. Despite all this, the market pressure for private cloud is so great that cloud computing vendors are finding ways to deliver private cloud anyway. Let’s take a deeper look at what’s going on here.

What’s Behind The Demand For Private Cloud?
The desire for private cloud is easy enough to appreciate. Organizations are enamored with the benefits of cloud computing but don’t like certain aspects of it, such as the loss of direct control over their assets or sharing resources with other tenants in the cloud. This is where the paradox comes in, because management by cloud data centers and shared resources are core to what cloud computing is and why its costs are low. The market isn’t required to be logical or think through the details, however, and when there’s sufficient demand vendors find ways to innovate. Thus, while private cloud may seem at odds with the general premise of cloud computing, it turns out we need it and will have it.

There are some other drivers behind the need for private cloud that are hard to get around. Governments may have requirements for physical control of data that simply cannot be circumvented. In some countries there are regulations that business data must be kept in the country of origin. Another influence is the future dream of things working the same way in both the cloud and the enterprise. When that day comes, solutions won’t have to be designed differently for one place or the other and enterprises will be able to move assets between on-premise and cloud effortlessly.

Defining Private Cloud
How then is private cloud to be brought about? This is where we get into many different ideas about what private cloud actually is. My pet peeve is people who use the term private cloud without bothering to define what they mean by it. Let’s take a look at understandings that are in widespread use.

1. LAN Private Cloud
Some people use private cloud to simply mean their local network, similar to how the Internet can be referred to as the cloud without any specific reference to cloud computing proper. This use of the term is rather non-specific so we can’t do much with it. Let’s move on.

2. Gateway Private Cloud
This use of private cloud centers on the idea of securely connecting your local network to your assets in the cloud. Amazon’s Virtual Private Cloud is described as “a secure and seamless bridge between a company’s existing IT infrastructure and the AWS cloud” which “connects existing infrastructure to isolated resources in the cloud through a VPN connection.” In the Windows Azure world, Microsoft is working on something in this category called Project Sydney. Sydney was mentioned at PDC 2009 last year but until it debuts we won’t know how similar or different it will be to the Amazon VPC approach. Stay tuned.

This type of private cloud is valuable for several reasons. It potentially lets you use your own network security and operations monitoring infrastructure against your assets in the cloud. It potentially lets your cloud assets access something on your local network they need such as a server that you can’t or won’t put in the cloud.

3. Dedicated Private Cloud
In this flavor of private cloud you are using a cloud computing data center where an area of it is dedicated for just your use. From this you get the benefits you’re used to in the cloud such as automated provisioning and management and elasticity, but the comfort of isolation from other tenants.

Microsoft Online Services has offered this kind of private cloud with a dedicated version of the Business Productivity Online Suite (“BPOS-D”) for customers with a large enough footprint to qualify.

It seems axiomatic that dedicated private cloud will always be more expensive than shared use of the cloud.

4. Hardware Private Cloud
In hardware private cloud, cutting edge infrastructure like that used in cloud computing data centers is made available for you to use on-premise. Of course there’s not only hardware but software as well. Microsoft’s recent announcement of the Windows Azure Appliance is in this category.

The nature of hardware private cloud makes it expensive and therefore not for everybody, but it is important that this kind of offering exist. First, it should allow ISPs to offer alternative hosting locations for the Windows Azure technology in the marketplace. Secondly, this allows organizations that must have data on their premises, such as some government bodies, to still enjoy cloud computing. Third, this solves the “data must stay in the country of origin” problem which is a significant issue in Europe.

Is there something like the hardware private cloud that’s a bit more affordable? There is, our next category.

5. Software Private Cloud
Software private cloud emulates cloud computing capabilities on-premise such as storage and hosting using standard hardware. While this can’t match all of the functionality of a true cloud computing data center, it does give enterprises a way to host applications and store data that is the same as in the cloud.

An enterprise gets some strong benefits from software private cloud. They can write applications one way and run them on-premise or in the cloud. They can effortlessly move assets between on-premise and cloud locales easily and reversibly. They can change their split between on-premise and cloud capacity smoothly. Lock-in concerns vanish. One other benefit of a software private cloud offering is that it can function as a QA environment—something missing right now in Windows Azure.

We don’t have software private cloud in Windows Azure today but there’s reason to believe it can be done. Windows Azure developers already have a cloud simulator called the Dev Fabric; if the cloud can be simulated on a single developer machine, why not on a server with multi-user access? There’s also a lot of work going on with robust hosting in Windows Server AppFabric and perhaps the time will come when the enterprise and cloud editions of AppFabric will do things the same way. Again, we’ll have to stay tuned and see.

Should I Wait for Private Cloud?
You may be wondering if it’s too soon to get involved with cloud computing if private cloud is only now emerging and not fully here yet. In my view private cloud is something you want to take into consideration—especially if you have a scenario that requires it—but is not a reason to mothball your plans for evaluating cloud computing. The cloud vendors are innovating at an amazing pace and you’ll have plenty of private cloud options before you know it. There are many reasons to get involved with the cloud early: an assessment and proof-of-concept now will bring insights from which you can plan your strategy and roadmap for years to come. If the cloud can bring you significant savings, the sooner you start the more you will gain. Cloud computing is one of those technologies you really should get out in front of: by doing so you will maximize your benefits and avoid improper use.

There you have it. Private cloud is important, both for substantive reasons and because the market is demanding it. The notion of private cloud has many interpretations which vary widely in nature and what they enable you to do. Vendors are starting to bring out solutions, such as the Windows Azure Appliance. We’ll have many more choices a year from now, and then the question will turn from “when do I get private cloud” to “which kind of private cloud should we be using?”

And please, if you have private cloud fever: please explain which kind you mean!

1 comment:

Anonymous said...

Thank you David, I found this article enlightening.
--Craig Erickson, PacWest