to execute linear replacement by utilizing the wspeed particularly the speed of data transferred from the host to the optical disc r p device is recorded into the wspeed area the optical disc r p device then compares the recorded speed of the data transfer with the speed by which the data is being written into the optical disc to determine whether to allow linearrepla 1 cement if the transfer speed of data from the host is close to the writing speed of the data into the optical disc execution of linear replacement slows down the writing of data thereby reducing the speed of data transfer and increasing the data transfer time on the other hand if the transfer speed is significantly slower than the writing speed slowing down the writing of data would not affect the data transfer time accordingly when the transfer speed is lower than the writing speed by a predetermined amount linear replacement is executed except when real time processing is required the host may determine and control whether to execute linear replacement utilizing the wtype flag and or the optical disc r p device may determine whether to execute linear replacement utilizing both the wtype flag and wspeed referring to fig5 if data to be.