The IBM 3850 Mass Storage System (a.k.a The MSS) was debuted in October of 1974. It was a hybrid type device using the then very popular IBM 3330 disk subsystem. It was used to hold large amounts of infrequently accessed data in mainframe environments by creating images of disk devices. It consisted of a library of cylindrical plastic cartridges, two by four inches each containing a tape spool. These 50 MB cartridges were held in a hexagonal array of bins. In August 1986 it was discontinued.
In the late 60’s IBM engineers in Boulder, Colorado, began development of a low-cost mass storage system based on magnetic tape in cartridges. It was code named “Comanche”.
There were many marketing studies and design changes were made during the first few years of the 70s before its October 1974 debut.
Eventually there would be eight models of the MSS each with different storage capacities and staging capabilities
– The entry version accommodated 706 tape cartridges with a capacity of 35 Gig.
– The largest version held 472 Gig.