Patent ID: 7664884
Filing Date: 2010-02-16
Classification: G06F,G11B,Y02D

Abstract:
1. A media drive that communicates with a host by means of serial communications, said media drive comprising: a temporary storage unit which temporarily stores transfer data read out from a medium; a serial communication unit which transfers, to the host, the transfer data read out from the temporary storage unit; a command execution controller which controls the execution of one or more commands so as to generate a transfer unnecessary period during which the one or more commands and the transfer data need not be exchanged with the host; and a communication controller which brings the serial communication unit into a power save mode during the transfer unnecessary period; wherein the command execution controller calculates an optimum start timing of data transfer, at which the transfer data is transferred from the temporary storage unit to the host, so as to extend the transfer unnecessary period and begin the power save mode; wherein the optimum start timing of data transfer is calculated on the basis of a medium transfer rate at which the transfer data is read out from the medium into the temporary storage unit, and a host transfer rate at which the transfer data is transferred from the temporary storage unit to the host; wherein the optimum start timing of data transfer occurs prior to filling the temporary storage unit so that transfer of data to the host is not delayed; wherein said medium has a plurality of zones and a plurality of medium transfer rates that differ from one another on a zone basis; wherein since it is defined that a period of time required to transfer data to the host at the host transfer rate is a host transfer time, and that a period of time required to read out data into the temporary storage unit at a medium transfer rate corresponding to each of the zones is a medium transfer time, said command execution controller is configured to determine the read timing and the data transfer timing on the basis of the host transfer time and the medium transfer time corresponding to each of the zones; and wherein said transfer data is formed of a plurality of sectors and said command execution controller calculates a number of read-ahead sectors by multiplying the number of the sectors of the transfer data by a read-ahead ratio for each zone, which is calculated by dividing the host transfer time per sector by the medium transfer time per sector and subtracting the quotient from 1, and then adopts, as the data transfer timing, timing at which the transfer data, the size of which is equivalent to the number of read-ahead sectors, has been read out from the medium into the temporary storage unit; wherein the host transfer rate is greater than the medium transfer rate.