Focusing on the services is, to my mind, critical, because the whole point of cloud computing is to deliver a more satisfactory set of IT services, not to make infrastructure management more convenient. Put another way, unless cloud computing provides greater responsiveness and higher satisfaction to application users, it misses the mark. For this reason, I have chosen to depict the internal cloud as a set of services rather than a set of software components.
Below the line resides Data Center Operations, which is responsible for infrastructure management and delivery of core computing capabilities:
Virtual resources: Storage, machines, and networking. Each of these resources must be available on demand by Business IT—immediately and at the necessary scale; of necessity, this implies a fully virtualized set of resources. The ability to supply requested capacity is a challenge; as the Berkeley RAD report noted, at some point internal resources will exhaust. However, for most service requests, exhaustion will not be a problem. However, the resource requests are likely to vary, with the amount of variability falling along some kind of distribution curve. Certainly, one should expect that reducing the friction for computing resources will undoubtedly increase the overall amount of resources called for. The effort to achieve a fully virtualized environment should not be underestimated. Assignment of storage and network resources as virtualized resources requires that capacity be staged and be capable of being assigned without human intervention. A key issue for storage and networking is that additional hardware is typically required to support dynamic assignment.
Automated Sys Admin: To emulate the public cloud providers like Google and Amazon in terms of both responsiveness and economics, system administration must move from a manual or semi-automated (often via home-grown Perl scripts indecipherable to any but the original creator) process to one that is completely hands-off in terms of individual actions like assigning storage, etc. In fact, the administration neeeds to be completely automated and driven by policy.
That is to say, once physical resources are put into operation, fully virtual-capable and ready to have capacity assigned, no further human intervention to assign or manage the resources can take place. The individual actions to assign those virtual resources must be initiated by calls from other software applications. To the extent that the effort of an individual sys admin is required to provision a resource request, the private cloud has a hole in its fabric. Between the resources themselves being fully virtualized, and the management of those resources being fully automated, the data center may be said to support the "huge resources" and "no commitment" elements of the Berkeley RAD Lab definition. We will return to the third element (pay by-the-drink) in a subsequent post.
Capacity Planning: The private cloud inventory management. It doesn't take a rocket scientist to see that doling out resources in a highly automated fashion, especially when the reduced friction promises to increase overall demand for computing resources, means that private clouds will require much more careful attention to the inventory of underlying physical resources. An analogy might be to the highly optimized supply chain of Wal-Mart—it keeps its shelves filled in the face of high demand by careful monitoring of overall demand and very robust ability to deliver goods as needed to replenish stock. in a private cloud, IT operations will need to track available computing resources with an eagle eye to ensure that capacity is always available to be assigned as demanded by application users.
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