A tape drive may calculate a slope for each of the timing-based-servo marks in a timing-based-servo group. The timing-based-servo marks are arranged in one or more M-patterns. The tape drive may average the slope for each of the timing-based-servo marks across the one or more M-patterns. The tape drive may generate a least-squares assessment of the averaged slope. The tape drive may determine, from the least-squares assessment, whether the averaged slope is demonstrative of tape-creep.

A tape drive allows for an increased track density by partially overlapping adjacent tracks as each successive track is written. Each successive track overwrites a portion of the width of the previous track, thereby reducing the width of the previous track. This process can be applied repeatedly thereby producing an arrangement of shingled data tracks across the width of the tape. In an embodiment, single-pass verification of data written in this manner is accomplished using a head assembly with two read heads per track. A first read head positioned behind the write head verifies that the data written is correct, and a second read head positioned over the previous track verifies that data on the previous track remains intact after being partially overwritten.