Bulk storage requirements in large-scale scientific calculations

The experience and plans of three scientific computing installations with bulk storage are reviewed with respect to capacity requirements, reliability enhancement, and the avoidance of recording delays. The bulk storage requirements of experimental data bases, array storage for large-scale scientific calculations, and large output files are reviewed. Results are presented of a survey of tape libraries in scientific computing installations. From user experience, applications, and the survey results, requirements for two classes of bulk storage devices emerge: dynamic bulk storage devices and archival bulk storage devices. Dynamic bulk storage devices are accessed repeatedly during the calculation, hence the access and bandwidth requirements must be comparable to current large-capacity disks, and capacity should be on the order of 10¹¹bit. Archival bulk storage devices are used largely at the beginning or at the end of a calculation, so access and bandwidth requirements are somewhat relaxed with respect to dynamic bulk storage, but capacity requirements should be at least 10¹²bit.