1. A computer program product for storage and processing node placement planning in a virtualized storage area network (SAN) data center environment, the computer program product comprising a non-transitory computer readable storage medium having computer readable program code embodied therewith, said program code being executable by a computer to: receive a resource graph describing SAN's resources, said graph includes a plurality of resource nodes, each of the resource nodes providing one or more resources for virtual machine applications, said applications and the resource nodes being in communication with the SAN, and the SAN's resources include processing and storage resources; receive virtual machine applications, each of said applications requiring a particular amount of a processing resource element and a particular amount of a storage resource element; determine a coupled placement of the processing element and the storage element for each of said applications on a coupled pair of the resource nodes, using an algorithm that implements a cost function that determines affinities between processing nodes and storage nodes for each of said applications of a particular workload, wherein the algorithm minimizes a cost factor of the cost function, wherein said determining the coupled placement is based on a specified throughput and a distance factor between the coupled pairs of resource nodes; wherein, said coupled placement for each of said applications identifies the particular amount of processing resource element placed on a first node for providing a processing resource and the particular amount of storage resource element placed on a second node for providing a storage resource for that application, the first node and the second node being connected as a coupled pair, and determining said coupled placement is performed with different coupled pairs having varying degrees of affinity; and compare, said coupled placement for each of said applications, based upon the cost function applied to particular application item placements on particular coupled nodes.