1. A method of data storage system modeling comprising: receiving, at a first data storage system, information representing a workload for performing I/O operations directed to a set of one or more logical devices having storage provisioned on a set of one or more physical devices of a second data storage system, wherein at least some of the information representing the workload is obtained by performing discovery processing to discover performance characteristics of the set of one or more physical devices, said discovery processing including: receiving, at the first data storage system, a plurality of I/O operations from a client directed to the set of one or more logical devices having storage provisioned on the set of physical devices of the second data storage system; issuing, by the first data storage system to the second data storage system, the plurality of I/O operations; and obtaining, at the first data storage system in response to said issuing, a set of performance data representing the workload for the plurality of I/O operations directed to the set of logical devices having storage provisioned on the set of one or more physical devices of the second data storage system; and modeling performance of the second data storage system in accordance with the workload.