level is a grid abstract machine, which consists of a collection of typed nodes -- data nodes (purple), director nodes (red), management nodes (orange), and various processing nodes (not shown), which might include a stand-alone MySQL or Oracle 10g node or other applications. Assume the nodes are all similarly provisioned -running the same operating system with similar memory size. We can view the entire grid as a resource pool -- for many applications, collections of various types of nodes (such as data, director, and management) are checked out or back in as a group. Most of them are data nodes -- that is, they contain portions of files or relations or, really, any data resource. Director nodes receive requests and queue them for data nodes; such requests include retrievals or insertions. Management nodes watch other nodes, checking
Craig W. Thompson