Tape Storage Device and Writing Method Therefor

A computer program product comprising a computer readable storage medium having a computer readable program for writing files of less than a fixed length to a tape medium stored therein, wherein the computer readable program, when executed on a computer causes the computer to:

• responsive to receiving a write request, write a first file from a host to the tape medium as a set of datasets (DSs) when receiving files from the host, wherein the write request for each file is accompanied by a synchronization command (Flush) after the write command (Write) from the host;
• store a DS number (DS#N) of a last DS and a WritePass (WP) number #M(WP#M) of a last write operation to nonvolatile memory;
• sequentially write DSs filled with the first file and a second file to a DS following the last DS containing the first file to the tape medium when receiving the second file following the first file;
• assign incremental DS numbering and WP number #M+1 to the DSs containing the second file and the first file;
• store the DS numbers and the WP number associated with first file and the second file to the nonvolatile memory
• overwrite a DS filled with the remaining portion of the first file, the second file, and a third file as DS#N and WP#M+2 when receiving the third file following the second file;
• write the remaining portion after DS#N as incremental DS numbering to the tape medium:
• and
• store information regarding WP#M+2 assigned to the DS numbering to the nonvolatile memory.

A tape recording device for recording in fixed-length data set (DS) units and for writing a file to a tape medium in accordance with a file writing request from a host, the tape recording device comprising:

• a buffer for temporarily storing files from the host;
• and
• a read/write control mechanism for reading and writing files to and from the tape medium in data set (DS) units, wherein the read/write control mechanism executes:
• responsive to receiving a write request, writing a first file from the host to the tape medium as a set of datasets (DSs) when receiving files from the host, wherein the wherein the write request for each file is accompanied by a synchronization command (Flush) after the write command (Write) from the host;
• storing a DS number (DS#N) of a last DS and a WritePass (WP) number #M(WP#M) of a last write operation to nonvolatile memory;
• sequentially writing DSs filled with the first file and a second file to a DS following the last DS containing the first file to the tape medium when receiving the second file following the first file;
• assigning incremental DS numbering and WP number #M+1 to the DSs containing the second file and the first file;
• storing the DS numbers and the WP number associated with first file and the second file to the nonvolatile memory;
• overwriting a DS filled with the remaining portion of the first file, the second file, and a third file as DS#N and WP#M+2 when receiving the third file following the second file;
• writing the remaining portion after DS#N as incremental DS numbering to the tape medium;
• and
• storing information regarding WP#M+2 assigned to the DS numbering to the nonvolatile memory.