Limitations of Traditional, Track-based Tape Technology The tape back-up systems of today, except for VXA Packet Drives, utilize track-based technology. It is a technology that was invented decades ago and has not changed significantly since that time. The challenge with today’s track-based tape systems is that they rely on an extremely tight head-to-tape alignment to write and then to read/restore the data. In fact, the allowable tolerance for their head-to- tape alignment is literally microscopic which not only makes them expensive to build, but also makes them more prone to errors. The Head-to-tape Alignment Problem. “ Tracking” tape drives use magnetic heads to write data in long, narrow tracks to the tape surface. The tracks are written sequentially with very strict specifications as to how the data is physically placed on the tape in linear or helical tracks. In like manner, tracking tape drives read data back from the tape by having their heads sequentially trace the outline of each tiny data track over relatively large blocks of data. Problems occur when a data track on a tape gets out of alignment with the reading heads by even a microscopic amount. When a misalignment occurs, the data cannot be read and thus is not restored. The track is an extremely long set of data saved on thin plastic material, making it easy for the track to become curved or tilted due to deformation of the medium. If the track becomes distorted, or if the angle of the track were to differ from the angle of the path of the Read head, then a read data error occurs (see Figure 1). There are many factors that contribute to changes in track geometry. In normal storage environments, tracks tilt and bend due to temperature, humidity, tape wear, drive tension variations, and accumulated debris. Interchange. In addition to changes in track geometry, differences in drive mechanisms can affect the ability of one drive to read a tape written by another drive. The complexity of the design and related stringent tolerances impact the ability to exchange media between identical drives. Through use and over time, the alignment of heads in the tape drive can also drift, further decreasing the long-term reliability of data restore and interchangeability. p1   p2   p3   p4   p5   p6