1. A method, performed by at least one computing system having a processor and memory, for calculating storage cost information in a computer network, the method comprising: identifying, by the computing system, multiple data storage devices in the network accessed by a plurality of users, the multiple data storage devices comprising primary data storage devices and secondary data storage devices, wherein the primary data storage devices are included in a first storage operation cell that is associated with primary copies of data, and include disk-based data storage media, and the secondary data storage devices are included in a second storage operation cell that is associated with secondary copies of data, and include tape-based data storage media and store one or more secondary copies of at least some of the data stored on the primary data storage devices; receiving, from the first storage operation cell, first information associated with at least a first primary copy stored on at least a first primary data storage device of the primary data storage devices, the first primary copy associated with a subset of one or more of the plurality of users; receiving, from the second storage operation cell, second information associated with at least a first secondary copy stored on at least a first secondary data storage device of the secondary data storage devices; processing, by the computing system, the first and second information to determine that the first secondary copy comprises a copy of the first primary copy and that the first primary copy and the first secondary copy are both associated with the subset of the plurality of users; determining primary storage cost data, wherein the primary storage cost data indicates a cost of using a quantity of storage space of the first primary storage device for a unit of time; determining secondary storage cost data, wherein the secondary storage cost data indicates a cost of using a quantity of storage space of the first secondary storage device for a unit of time; determining primary storage usage data associated with usage of the first primary data storage device by the subset of the plurality of users; determining secondary storage usage data associated with usage of the first secondary data storage device by the subset of the plurality of users; and calculating, by the computing system, a storage cost associated with the subset of the plurality of users based on the primary storage usage data, the secondary storage usage data, the primary storage cost data, and the secondary storage cost data.