1. A computing system for simulating data storage operations for testing and evaluating components of a storage operation system in a computer network, the computing system comprising: one or more computers each comprising: one or more processors; and a memory storing a program of instructions to be executed by the one or more processors; the program of instructions stored in the memory of the computers comprising: at least one virtual data agent component assigned to obtain application-specific data from an application for execution on one or more of the computers, the virtual data agent being implemented with a plurality of data-type specific data agents that obtain different types of data from the application; a plurality of different media management components for execution on one or more of the computers, in communication with the virtual data agent component to receive the application-specific data obtained by the virtual data agent, wherein the different media management components are configured to communicate with and perform storage operations on different types of storage devices; a storage device emulation module for execution on one of the computers, the storage device emulation module comprising a plurality of different types of simulated storage devices to simulate characteristics of the different types of storage devices; and a storage manager component in communication with the virtual data agent, the storage device emulation module, and the media management components; wherein when the program of instructions is executed by the one or more processors in the one or more computers: the virtual data agent component obtains application-specific data from an application executing on one or more of the computers and identifies storage policy, preferences and criteria indicating the type of storage device to be used to store the data; the storage device emulation module provides characteristics of the different types of simulated storage devices provided by the storage device emulation module; the storage manager component assigns the different media management components to the different types of simulated storage devices based on the type of storage device to be used to store the data and the characteristics of the different types of simulated storage devices provided by the storage device emulation module; the storage device emulation module executing on one of the computers, simulates different types of storage devices using different types of simulated storage devices; once assigned by the storage manager component, the different media management components are in communication with the at least one virtual data agent and the different types of simulated storage devices, and receiving the data from the virtual data agent and directing storage operations on different types of simulated storage devices; and the different types of simulated storage devices, under direction of the storage manager component, simulate storage operations associated with the data generated by the virtual data agent on the different types of simulated storage devices, thereby testing and evaluating components of the storage operation system in the computer network.