LTO Technology Primer - Part Two
The movement of the head is controlled by a servo system that uses information encoded in bands at the top and bottom of each data band. The servo bands are written on the tape at the time the cartridge is manufactured. Two servo bands are used simultaneously to provide dual sources of servo information. This provides for more accurate positioning of the head, and also provides tolerance for media defects in the servo area.
The format specifies six nominal servo positions within each servo band. The distance between two adjacent servo positions corresponds to the distance apart that the data tracks are written.
The head contains eight elements for the first generation product. The read and write elements may be stacked, staggered, or arranged in separate modules. This example shows the elements in the stacked configuration.
During a write operation with an eight element head, top servo zero, or TS0, is centered on servo position zero, as the eight elements write data in the first track group. When the head senses the end of the tape marker, top servo one, or TS1, aligns with servo position five, as the second track group is written in the reverse direction. The process of writing the full length of tape in one direction takes just a few minutes.