1. A data processing system comprising: a master storage system, including storage media and a first disk controller for storing and accessing original data on the storage media; a plurality of secondary storage systems each for storing copies of the original data, each of the secondary storage systems including a second disk controller; the first and second disk controllers operating to receive I/O requests for access to the original data and original data copy, respectively, and storing the data using block level I/O; a manager processor coupled to the master storage system having a file system process to respond to file level I/O requests from application programs for accessing the original data, the manager processor maintaining data structures identifying the locations of file data corresponding to the original data stored at the master storage system; at least two server processors coupled to ones of plurality of secondary storage systems, each of the server processors having copies of at least portions of the data structures for locating file data on the secondary storage systems; whereby the manager processor operates to write changes to file data to make corresponding changes to the original data changes the data structure to identify the changed data, and to notify the server processors that original data structures have been changed; and whereby copies of the changed original data and data structure are sent by the master storage system to the secondary storage systems.