Patent ID: 8693129
Filing Date: 2014-04-08
Classification: G11B

Abstract:
1. A transport speed adjustment method to be employed in a tape drive capable of switching a transport speed of a tape medium among multilevel speeds, the method comprising the steps of: receiving data from a host device through a network; temporarily storing the received data in a buffer memory; transporting the tape medium in a longitudinal direction thereof; writing the data in the buffer memory into a track formed to extend in a transport direction of the tape medium; calculating a first transfer rate, which is a data transfer rate between the host device and the tape drive; selecting, from adjustment modes consisting of a speed switch mode and a constant speed mode, an adjustment mode corresponding to the calculated first transfer rate, by referring to a mode selection table in which such an adjustment mode more effective in reducing back hitches is defined in accordance with the first transfer rate, the transport speed being switched between a first transport speed and a second transport speed in the speed switch mode, the transport speed being fixed at the second transport speed in the constant speed mode, the first transport speed being a highest speed of one or more transport speeds at which the tape drive can be caused to operate under a condition that a second transfer rate, which is a data transfer rate between the buffer memory and the tape medium, is lower than the first transfer rate, the second transport speed being one-level higher than the first transport speed; causing the tape drive to operate at the first transport speed at a beginning of data writing, in response to selection of the speed switch mode; obtaining a time required to switch the transport speed of the tape medium from the first transport speed to the second transport speed, in response to the selection of the speed switch mode; calculating, from the first transfer rate and the required time, a data volume expected to be received from the host device during switch of the transport speed, as a threshold; monitoring whether or not an available data storage capacity of the buffer memory reaches the threshold while data is written at the first transport speed in the speed switch mode; and stopping writing the data and switching the transport speed of the tape medium to the second transport speed, in response to a monitoring result that the available capacity reaches the threshold.