Abstract: A tape drive capable of switching the transport speed of a tape medium among multilevel speeds calculates a data transfer rate from/to a host device, and selects an adjustment mode of the transport speed of the tape medium from a constant speed mode and a speed switch mode according to the calculated data transfer rate. The tape drive in the speed switch mode, pauses a data write or read operation to switch the transport speed of the tape medium while data is written at a first transport speed and when an available capacity of a buffer memory reaches a data volume to be received from the host device during switching of the transport speed and is read out at the first transport speed and when a data volume of a buffer memory reaches a data volume to be transmitted to the host device during switching of the transport speed.

Abstract: In one general embodiment, a tape drive system includes: a read channel; a write channel; logic configured to receiving a request for a write operation to be performed in a tape drive; logic configured to determine an optimum a write procedure in response to receiving the request, the determining being based on expected writing times of each of a plurality of write procedures and an expected transaction size of a next write operation; and logic configured to invoke the determined optimum write procedure in response to determining the optimum write procedure.

Abstract: In one general embodiment, a method includes receiving a request for a write operation to be performed in a tape drive, determining an expected transaction size of a next write operation, comparing the expected transaction size of the next write operation to each of a first transaction size threshold and a second transaction size threshold in response to receiving the request, determining an optimum a write procedure based at least in part on the comparison, and invoking the optimum write procedure in response to determining the optimum write procedure, wherein the first transaction size threshold is greater than the second transaction size threshold, and wherein the optimum write procedure is selected from the group consisting of: a backhitch write procedure, a same wrap backhitchless flush (SWBF) write procedure, and a recursively accumulating backhitchless flush (RABF) write procedure.

Abstract: In one embodiment, a tape drive system includes a read channel, a write channel, logic adapted for accessing data sets using the read channel and/or the write channel, logic adapted for counting each data set access using the read channel that used error recovery procedure (ERP), logic adapted for counting each data set access using the read channel that did not use ERP, logic adapted for counting each data set access using the write channel that used ERP, logic adapted for counting each data set access using the write channel that did not use ERP, and logic adapted for accessing subsequent data sets using the read channel and/or the write channel, wherein any subsequent data set access that uses ERP is accessed using an initial ERP step characterized by a first tape speed, wherein the first tape speed is selected at least partially based on the counts.

Abstract: For determining an access sequence of a plurality of data groups stored on a tape medium, a first data group in the access sequence is selected based on which data group in the plurality of data groups has a beginning closest to a current position of the tape medium. A second data group in the access sequence is selected based on which remaining data group in the plurality of data groups has a beginning closest to an end of the first data group in the access sequence.

Abstract: For determining an access sequence of a plurality of data groups stored on a tape medium, a first data group in the access sequence is selected based on which data group in the plurality of data groups has a beginning closest to a current position of the tape medium. A second data group in the access sequence is selected based on which remaining data group in the plurality of data groups has a beginning closest to an end of the first data group in the access sequence.

Abstract: A data-overwriting technique that facilitates determining whether data is new or old. A tape recording apparatus includes: a receiving unit for receiving information on overwrite starting position and an overwrite request; a trying unit for trying to determine a beginning position of a data unit; an overwrite executing unit for executing overwriting from the determined overwrite starting position in response to a success of the determination by the trying unit; and a type judging unit for judging whether the data unit that is recorded at the overwrite starting position is a null data unit or not in response to a failure of the determination by the trying unit. The trying unit responds to judgment that the data unit is the null data unit by determining a beginning of a data unit following the data unit as the overwrite starting position.

Abstract: In a controller of a tape drive, when a command processing unit receives a Write FM0 command, a channel input/output unit writes the data in the buffer and a speculative FM onto the tape, and a CM input/output unit records speculative FM presence information in a cartridge memory. When the command processing unit receives Write FM1 command next, the CM input/output unit erases the speculative FM presence information from the cartridge memory. When the command processing unit receives a command other than Write FM1 command next, the channel input/output unit overwrites a speculative FM.

Abstract: A data-overwriting technique that facilitates determining whether data is new or old, when reading thereof. A tape recording apparatus includes: a receiving unit for receiving information on overwrite starting position and an overwrite request; a trying unit for trying to determine a beginning position of a data unit based on the information on an overwrite starting position, wherein the data unit is a unit of writing data recorded on a tape medium; an overwrite executing unit for executing overwriting from the determined overwrite starting position in response to a success of the determination by the trying unit; and a type judging unit for judging whether the data unit that is recorded at the overwrite starting position is a null data unit or not in response to a failure of the determination by the trying unit. The trying unit responds to judgment that the data unit is the null data unit by trying to determine a beginning of a data unit following the data unit as the overwrite starting position.

Abstract: Provided is a terahertz wave generator that improves efficiency of generating a terahertz wave. The terahertz wave generator includes a generating layer for generating the terahertz wave, a waveguide layer for propagating excitation light entering the generating layer and a terahertz wave generated by the excitation light entering the generating layer, and a first confinement layer for confining in the waveguide layer the excitation light propagating in the waveguide layer and the terahertz wave propagating in the waveguide layer. The generating layer, the waveguide layer, and the first confinement layer are laminated in the stated order.

Abstract: Data of a target capacity calculated by a nominal capacity of a tape medium minus a data capacity lost due to execution of backhitchless writing is written to the tape medium. In a tape drive, a command processing unit 41 receives a synchronization command, and a buffer management unit passes data in a buffer to a channel input-output unit. Upon completion of writing the data to the tape, a backhitch determination unit determines whether a mode information storage unit stores information indicating that a high data rate mode is on, whether data of a target capacity can be written to the tape, and whether the written data can be read at a target read data rate. An operation signal output unit issues a command to execute backhitch in case these conditions are not satisfied.

Abstract: A tape drive, tape drive recording system, and method are provided for improving tape speed selection during data transfer. The tape drive comprises a buffer, a tape for recording the data to be temporarily stored in the buffer, and a read head. The tape drive further comprises a reading controller that initially sets a tape speed such that a drive transfer rate matches a host transfer rate as closely as possible and that drives the tape at the tape speed. To address backhitching caused by one or more host transfer halts, the reading controller subsequently adjusts the tape speed such that the drive transfer rate is lower than the host transfer rate by recalculating the host transfer rate in consideration of the host transfer and the host transfer halt and setting the tape speed such that the drive transfer rate matches the recalculated host transfer rate as closely as possible.

Abstract: A tape drive, tape drive recording system, and method are provided for improving tape speed selection during data transfer. The tape drive includes a buffer, a tape for recording the data to be temporarily stored in the buffer, and a read head. The tape drive further includes a reading controller that initially sets a tape speed such that a drive transfer rate matches a host transfer rate as closely as possible and that drives the tape at the tape speed. To address backhitching caused by one or more host transfer halts, the reading controller subsequently adjusts the tape speed such that the drive transfer rate is lower than the host transfer rate by recalculating the host transfer rate in consideration of the host transfer and the host transfer halt and setting the tape speed such that the drive transfer rate matches the recalculated host transfer rate as closely as possible.

Abstract: Optical pulse compensator having a chirp unit including a normal dispersion fiber that provides a positive chirp to an input pulse and having a dispersion compensator including an anomalous fiber is provided. The nonlinear coefficient and the absolute value of the second-order group-velocity dispersion of the anomalous fiber that forms the dispersion compensator is set such that a soliton order becomes one or more, and the fiber length of the anomalous dispersion fiber is made to be equal to or smaller than a length required for optical soliton formation.

Abstract: For determining an access sequence of a plurality of data groups stored on a tape medium, a first data group in the access sequence is selected based on which data group in the plurality of data groups has a beginning closest to a current position of the tape medium. A second data group in the access sequence is selected based on which remaining data group in the plurality of data groups has a beginning closest to an end of the first data group in the access sequence.

Abstract: High performance is obtained without preventing achievement of a target read data rate. In a controller 16 of a tape drive, a command processing unit 41 receives a synchronization command, and a buffer management unit 42 passes data in a buffer to a channel input-output unit 43. Then, upon completion of writing the data to the tape, a backhitch determination unit 44 determines whether or not to execute backhitch. If it is determined that backhitch should be skipped, the speed determination unit 46 determines a tape speed that minimizes a sum of a time required to write data without backhitch within a range where a data amount of a monitor target is to be written in order to achieve a target read data rate, and a time required to write data with backhitch within the range. Then, an operation signal output unit 49 issues an instruction to change the tape speed to the determined tape speed after execution of backhitch.

Abstract: A data-overwriting technique that facilitates determining whether data is new or old. A tape recording apparatus includes: a receiving unit for receiving information on overwrite starting position and an overwrite request; a trying unit for trying to determine a beginning position of a data unit; an overwrite executing unit for executing overwriting from the determined overwrite starting position in response to a success of the determination by the trying unit; and a type judging unit for judging whether the data unit that is recorded at the overwrite starting position is a null data unit or not in response to a failure of the determination by the trying unit. The trying unit responds to judgment that the data unit is the null data unit by determining a beginning of a data unit following the data unit as the overwrite starting position.

Abstract: A tape drive capable of switching the transport speed of a tape medium among multilevel speeds calculates a data transfer rate from/to a host device, and selects an adjustment mode of the transport speed of the tape medium from a constant speed mode and a speed switch mode according to the calculated data transfer rate. The tape drive in the speed switch mode, pauses a data write or read operation to switch the transport speed of the tape medium while data is written at a first transport speed and when an available capacity of a buffer memory reaches a data volume to be received from the host device during switching of the transport speed and is read out at the first transport speed and when a data volume of a buffer memory reaches a data volume to be transmitted to the host device during switching of the transport speed.

Abstract: A method for controlling writing for a tape recorder that is connected to a host and sequentially records, as a transaction, a plurality of records that are transferred from the host and stored in a buffer is provided, including receiving a synchronous command for a first transaction from the host; in response to the synchronous command, sequentially writing the plurality of records stored in the buffer to a tape as the first transaction; receiving the size of a second transaction following the first transaction from the host; calculating time for a backhitch associated with an operation of the synchronous command for the first transaction on the basis of the size; and performing the backhitch on the basis of the time for the backhitch.

Abstract: Optical pulse compensator having a chirp unit including a normal dispersion fiber that provides a positive chirp to an input pulse and having a dispersion compensator including an anomalous fiber is provided. The nonlinear coefficient and the absolute value of the second-order group-velocity dispersion of the anomalous fiber that forms the dispersion compensator is set such that a soliton order becomes one or more, and the fiber length of the anomalous dispersion fiber is made to be equal to or smaller than a length required for optical soliton formation.