In my personal view, while Grid is about interoperability and federation, cloud is about hosting and on-demand provisioning of virtualized resources. I venture that these complementary technologies will coexist and cooperate at different levels of abstraction in future e-infrastructures. On one hand, clouds could help to overcome many of the barriers to grid adoption. On the other hand, clouds should take advantage of the research and development conducted by the grid community, for example in the adoption of standard grid interfaces and functionality for federation.
About Benefits Brought by Cloud to Grid
Cloud helps to simplify and optimize grid site operation, being fully transparent to end users. Grid middleware can operate in a transparent way on top of these virtualized computing resources, bringing about the development of virtual grid infrastructures, which brings numerous benefits: easy support for VO-specific worker nodes, reduction of gridification cycles, dynamic balance of resources between VO’s, fault tolerance of key infrastructure components, easier deployment and testing of new middleware distributions, distribution of pre-configured components, cheaper development nodes, simplified training machines deployment, performance partitioning between local and grid services, etc.
There is a growing adoption of cloud computing in grid sites. For example D-Grid in Germany, BigGrid in the Netherlands and EGEE in Europe are using OpenNebula (www.opennebula.org) to virtualize their grid services. Their aim is not only to bring to the e-Infrastructure ecosystem benefits in terms of simplification added flexibility but also to provide new the IaaS-like interfaces demanded by several user communities.
StratusLab (www.stratuslab.eu) is a new European Project aimed at bringing cloud and virtualization benefits to production grid infrastructures. The project will incorporate cloud and virtualization innovation into existing Grid infrastructures by integrating cloud technologies and services within Grid sites; and by enriching existing computing infrastructures with “Infrastructure as a Service” (IaaS) cloud like delivery paradigms.