Linear recording device for executing optimum writing upon receipt of series of commands including mixed read and write commands and method and program thereof

摘要

A tape drive is provided, which executes an optimum writing method even when overwrite is intervened between mixed read and write operations. When an overwrite command is received while executing the mixed operations, which writes to a predetermined tape position, when a tape position to overwrite on is encountered before the append-written data ending position of the tape (tape EOD), the overwritten tape position is regarded as the append-written data ending position of the tape (tape EOD) to update the tape EOD by the overwritten tape position. When a tape position to overwrite is encountered after the append-written data ending position of the tape (tape EOD), the overwritten tape position is updated by the append-written data ending position of a non-volatile memory (non-volatile EOD). The updating the EODs enhances the performance of the mixed read and write operations even when an overwrite command is intervening.

主权项

1. A system, comprising:
a tape device controller configured to:
couple to a read/write head configured to read data from a tape into a buffer and write data from the buffer onto the tape, wherein the tape is provided in a tape cartridge, and wherein the buffer is configured to store data related to reading and writing;couple to a non-volatile memory, wherein the non-volatile memory is configured to store data stored in the buffer in response to a write command;receive a series of commands, wherein each command causes movement of the tape to a tape position specified by the command, the series of commands including mixed read commands, overwrite commands, and append write commands, wherein the read commands include first, second, . . . , m-th, n-th . . . , read commands in this order, and wherein n=m+1;read data from a specified position of the tape and store the data read from the specified position of the tape in the buffer in response to a read command; andwrite data stored in the buffer starting from an appended data end position of the tape in response to an append write command.