Since the start of JET, an IBM mainframe has been the main platform for data analysis and storage. The mainframe was removed in June 2001 and Solaris and Linux are now the main data storage and analysis platforms. New data storage and retrieval systems have therefore been developed: the Data Warehouse, the JET Pulse File (JPF) server, and the Processed Pule File (PPF) system. These support access to the data from codes running on many distributed clients on platforms including Linux, Windows NT and Solaris at JET, and at other fusion laboratories using JET Remote Data Access (RDA) software and MDSplus. A requirement for all these systems was to insulate users from the change in architecture and operating system by supporting a programming interface identical to the old IBM systems. A further requirement was to improve the existing systems by using current technology to make the systems more maintainable, and allow extra functionality to be added in the future. The new systems had to be developed while JET operations continued in parallel. The new systems will be described, and the design decisions that led to the final systems will be outlined.