A survey and analysis has been made of high density mass storage systems for the Navy Fleet Material Support Office. The purpose of the project was to survey mass storage devices and systems and to select several devices for detailed analysis. Representative devices were analyzed in order to determine their suitability for various file management functions. The major conclusions of the study are the following: 1. Mass storage devices have high potential for those applications which have a requirement to store a large data base (10¹-10¹² bits) on-line. 2. Mass storage devices should be considered as supplements to conventional storage devices for large data base applications, and used as part of a hierarchical storage system, rather than as replacements for conventional storage quipment. 3. Mass storage devices are not competitive with conventional storage equipment for direct access processing. 4. Erasable mass storage devices are competitive with conventional storage equipment for sequential file processing. 5. Non-erasable mass storage devices are inappropriate for high activity file processing but can be employed to advantage in archival storage applications. 6. As in the case of conventional storage units, the file activity ratio is a prime consideration in the selection of a file processing technique for mass storage. Low activity ratios favor address look-up or calculation and direct file access. High file activity ratios favor batched input and sequential file