Embodiments of a data storage tape control system are disclosed that works
to prevent or reduce frequency of off-track errors. The invented method
slows tape speed in response to the writing head or writing element moving
transversely away from a track center a predetermined distance, called an
"off-center limit," wherein the off-center limit is part of the way to an
off-track error limit. The off-center limit is close enough to the center
of the track that the writing operation is still effective, but wherein
further movement out from the center would result in an off-track error
and possible overwriting or unreadable data. The tape speed reduction is
preferably done in increments until the writing head/element is closer to
the center of the track than the off-center limit. Speed reduction is
preferably done concurrently with writing, so that writing is not
interrupted. Although the tape speed is reduced, the overall efficiency of
writing may be increased compared to an operation in which off-track
errors and writing failures occur repeatedly, at least in part because of
high tape speeds.
