Nimbula's founders developed the Amazon EC2 public cloud system and are now working on Nimbula Director, which aims to partition internal cloud resources by authentication, along the lines of how EC2 works.
The Nimbula API, which is controlled by command line, Web user interface logic/selections, or customized/scripted applications, manages policy control (authentication, resources offered, tracking/monitoring), placement (assets used) and control (storage, networking, and configuration).
The API allows jobs to be created and executed on internal resources or into the public cloud depending on policies controlled through API. Maybe you execute internally and get one bill, or perhaps do the job on the public cloud and get a different bill -- all controlled via policy motivated by cost and audit/compliance needs.
Released into beta on Dec. 6, Nimbula Director is designed along the lines of Novell's Cloud Director -- to partition internal cloud resources into aggregate units, much as Managed Services Providers do. This multi-tenancy approach allows organizations to allocate, measure, then charge for the services rendered within the assigned aggregations.
VM instances and clusters that are "spun up" are much like the compute resources offered by Amazon and its public cloud competitors. We looked at an early release of Nimbula Director on Xen that uses a familiar REST/HTTP communications and control system managed from a small server.
Nimbula Director, on that server, spins up Xen VM instances through a seed node that in turn propagates the network with desired VMs. VM instances and their resources can be configured to launch, do their work, then go away (except for the bill, of course), similar to externally contracted/linked cloud resources.
Nimbula currently avoids Hyper-V and VMware hypervisor infrastructures in favor of Xen and KVM, giving Nimbula a more Linux-like flavor -- although managed instances are a function of what Xen and KVM support.
Read more about data center in Network World's Data Center section.