Aug 21, 2010

Private vs. Public Clouds -

There's an ongoing debate about whether companies should embrace the public cloud or invest in a private cloud. I think it's important to set the context by defining in

"The reality of what service to choose comes down to what fits with your company culture. Even though the cloud has its own level of security, a private cloud environment may make more sense for the more conservative enterprise" Forrester's James Staten

Private Cloud - Overview and Advantages
A private cloud is a highly virtualized cloud data centre, often located inside your company's firewall. It may also be a private space dedicated to your company within a cloud vendor data centre, designed to handle your compnay's workloads.

What sets a private cloud apart from a commercially-used public cloud is how the hardware is kept and maintained. Typically, the hardware is hosted and maintained on the company's own servers, within their own network infrastructure.

The main advantage one has with a privately-managed cloud is direct control over every aspect of the cloud’s implementation: the hardware, the networking, the operating system and other software used to create the cloud itself; the way security is implemented; even the APIs used (that is, if you’re using an open source system).

Key Characteristics
  • Provides self-service provisioning of hardware and software srouces
  • supports specific workloads
  • Optimizes the use of computing resources such as servers
  • provides a well-managed environment
  • automates management tasks ans lets you bill business units for services they consume
  • allows It to provisiton services and copte capabillity to internal users in a sel-service manner

Another advantage of a private cloud is that it can generally be built from reasonably current commodity hardware. The most stringent requirements, apart from disk space and memory, are processors that support virtualization -- e.g., the Intel VT-x or AMD’s AMD-V extensions.

Most server-grade hardware, and even a fair amount of desktop-grade hardware, sold in the last few years will sport such features. If the hardware is available and isn’t provisioned for anything -- or is being de-provisioned from other things -- it can be put to use as part of a cloud.

A third advantage is locality. A cloud hosted in your own datacenter, or on your own property, is far easier to move data into (and out of) than a cloud hosting elsewhere. If you have the servers on another floor and want to use a 30GB disk image as part of your cloud setup, it’s easy enough to just walk over there and add the disk to the cloud.

A fourth advantage is security -- that is, up to a point. If you are hosting your own cloud infrastructure on a private LAN, with no connections to the outside world, it’s theoretically a good deal easier to secure. Since it’s your network and your boxes, you can exercise that much more discretion over it. That said, this presumes you have good security protocols in place to begin with:

Sounds a lot like a public cloud - a private cloud exhibits the key characteristics of a public cloud, including elasticity, scalabillity and self-service prvovisioning. The major difference is CONTROL over the enviroment. In a private cloud, the customer controls the service management. (a good analogy would be Internet vs. Intranet).

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