A Borrowed Supercomputer
Back in 1974, the center began operation with a borrowed Control Data Corporation 6600 computer. Initially most users had to connect modems to their terminals and dial up this computer via telephone, though some early users were able to use the ARPA network for connectivity. In 1975, a CDC 7600 replaced the 6600. In 1976, dedicated, leased phone lines connected the center with the major fusion energy research sites, allowing users to log into the 7600 from their local DEC PDP-10 minicomputers. The machine was rapidly filled to capacity, and for a while we had to purchase additional 7600 time from Berkeley Lab.
The center acquired a Cray 1 in 1978 and soon became known as an innovator in the management and operation of supercomputers. We converted our 7600 operating system, utilities, and libraries to the new machine, creating the Cray Time Sharing System (CTSS) — the first timesharing system for a Cray — and demonstrating that the machine could be used interactively. CTSS was subsequently adopted by nine other computer centers.
With each new system, data storage capabilities had to evolve as well. When NERSC first opened its doors in 1974, files were typically measured in megabytes. In 1976, the center could store a whopping 19,200 megabytes of data, primarily on online disks and nine-track tapes. But back then, users’ computing needs, and the hardware and software available to meet them, were quite different too. For example, managing data required staffers to move around behind the scenes. When a user filed a request, an operator would retrieve the tape from a rack and load it, then notify the user that the data were available. In some cases, the tapes were stored in a separate building at LLNL and were often picked up by a staffer riding a bicycle! Fortunately, delivery of the Automated Tape Library in 1979 changed this practice by allowing hands-off access.
The world's first Cray 2, a four-processor system, was installed at the center in 1985. We had already spent two years preparing the CTSS operating system for multitasking. This preparation paid off when the Cray 2 was available to users only one month after delivery.
Over the next decade, NERSC continued to enhance the productivity of cutting-edge computer architectures. In August 1997, NERSC achieved a milestone: successfully stopping and restarting a number of scientific computing jobs on a Cray T3E without any data processing loss or discontinuity. Called "checkpointing," the stop/restart procedure is believed to be the first time such a procedure has been accomplished on a massively parallel processing (MPP) system. This accomplishment opened a new era of robust, reliable, production-mode MPP computing.