The MAC3091 and MAC3045 high-performance magnetic disk units were Fujitsu’s first 10,033 rpm magnetic disk units and were designed to address rising mainframe and workstation speeds. Fujitsu began shipping the units in March 1998.
To increase the units’ access speeds, Fujitsu used a faster disk rotational speed and added support for Ultra SCSI interfaces, which increased the SCSI throughput rate. As a result, the MAC3091 and MAC3045 achieved internal data transfer speeds of 27.5 MB per second, which was among the fastest magnetic disk speeds at the time. And with high-performance magneto-resistive (MR) heads, a new signal processing technology, and faster and more precise positioning, the MAC3091 reached a recording capacity of 9.1 GB and the MAC3045 4.5 GB. These models later evolved into the high-rpm version of Fujitsu’s Allegro series (denoted as Allegro-xxE: for example, Allegro-4LE) of enterprise magnetic disk units.
For the MAC3091 and MAC3045, Fujitsu introduced a number of innovations to reduce and eliminate disk vibration to attain 10,000 rpm or faster speeds with 95-millimeter-diameter disks. For the next-generation units (Allegro-5E), however, Fujitsu was forced to use a smaller internal disk size (84 millimeters instead of the normal 95 millimeters) while keeping the external 3.5-inch size to combat the heat and vibrations that accompanied the faster disk speeds.