Deleting files written on tape

Patent metadata

Field	Value
Publication number	US-9753930-B2
Application number	US-201514922492-A
Country	US
Kind code	B2
Filing date	Oct 26, 2015
Priority date	Nov 4, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A method for writing a file from an application of a host onto a tape includes sequentially receiving records forming the file from the application, adding a predetermined number of segments of dummy data (dummy records) subsequently to the plurality of records forming the file such that the records of the file and records of a subsequent file are not included in the same data set, interposing the dummy records between a final record of the file and a head record of the subsequent (next) file, to thereby construct at least one data set that is adjacent to one data set and does not include the records of the file, and writing a data set including the records of the file, a data set (dummy data set) including the final record of the file and the dummy records, and a data set including the subsequent file, onto the tape.

First claim

What is claimed is:

1. A method for writing, by a tape apparatus, a file from an application of a host onto a tape, the method comprising:
sequentially receiving a plurality of records forming the file from the application;
dividing the file;
adding a predetermined number of segments of dummy data (dummy records) subsequently to the plurality of records forming the file such that the records of the file and records of a subsequent file are not included in a same data set, the file being in a first data set and the subsequent file being in a second data set, wherein the predetermined number of segments of dummy records are added such that the first data set remains even after deletion of the file, wherein records within a particular data set are interleaved using an interleaving function;
interposing the dummy records data between a final record of the file and a head record of the subsequent file to construct a third data set that is adjacent to the first data set and does not include the records of the file; and
writing the first data set including the records of the file, a data set including the final record of the file and the dummy records, and the second data set including the subsequent file, onto the tape.

2. The method of claim 1 , wherein adding the predetermined number of segments of dummy data includes receiving the dummy data as the predetermined number of dummy records from the application.

3. The method of claim 1 , wherein adding the predetermined number of segments of dummy data and constructing the third data set are executed such that a head record of the file corresponds to a head portion of the data set.

4. The method of claim 3 , wherein the predetermined number of segments of dummy data are determined such that the location of the head record of the written file corresponds to a head portion of a fourth data set, an area after a final record in a final data set is filled with invalid data, and a fifth data set including the plurality of records of the file is written onto the tape.

5. The method of claim 1 , further comprising:
identifying a configuration of a fourth data set including records of extents into which the written file is fragmented; and
adding the dummy records subsequently to the records of the written extents and writing the file, the dummy records, and the subsequent file such that a next data set includes the subsequent file.

6. The method of claim 1 , wherein the application is a file system for the tape apparatus, the tape is divided into an index partition in which meta-information is stored and a data partition in which the records of the file are stored, and the file and a plurality of extents forming the file are written in units of records having a predetermined size.

7. The method of claim 1 , further comprising:
writing at least one data set at intervals of four meters from a writing position of a head data set of the tape; and
writing the at least one data set not including the first data set of the file, at a position of less than four meters.

8. The method of claim 1 , wherein the tape apparatus includes a linear tape filing system.

9. The method of claim 1 , wherein the predetermined number of dummy segments is based on a length of the tape being less than a maximum tape length, further comprising:
terminating the writing the first data set when a length of tape used for the written first data set reaches the maximum tape length.

10. The method of claim 9 , wherein the tape drive writes data while moving back and forth on wraps of a write region along the longitudinal direction of the tape, wherein the tape is divided into the two partitions from the beginning of the tape to the end of the tape, wherein the dummy records are a predetermined size, and wherein the two partitions are separated by a protection region, the method further comprising:
deleting information associated with the physically overwritten first data set from an index that includes information associated with the location of the overwritten first data set on the tape drive, wherein the index is updated every time the tape is taken out from the tape apparatus; and
writing an index file in an XML format onto the tape, wherein the index file includes a directory name, a file name, a file creation date, and position meta-information, the position meta-information including a position on the medium, a size, and an offset in the first file.

11. The method of claim 1 , wherein the tape is stored in a tape cartridge including a non-contact non-volatile memory.

12. The method of claim 1 , wherein the tape apparatus includes a buffer, a reading and writing channel, a head, a motor, reels on which the tape is wound, a read and write controller, a head position controlling system, and a motor driver.

13. The method of claim 1 , wherein the file is written onto to the tape such that the file may be completely deleted at a later time by the tape apparatus.

14. A method for deleting a first file from a tape, the method comprising:
receiving a request to delete the first file from an application, wherein the tape includes one or more files and dummy data interposed between each of the one or more files;
acquiring a first head position of a first data set including a first head record of the first file to be deleted;
acquiring a second head position of a second data set including a second head record of a second file written immediately after the first file to be deleted; and
writing a high frequency pattern from the first acquired head position to the second acquired head position.

15. The method of claim 14 , further comprising:
identifying a position of data of the first file to be deleted, on a basis of meta-information stored in an index partition;
identifying a number of the first data set including data of the first file and dummy records; and
physically overwriting the first data set using the high frequency pattern.

16. The method of claim 15 , wherein the first file was written onto the tape from an application of a host by a tape apparatus, wherein the tape apparatus includes a linear tape filing system.

17. The method of claim 16 , wherein the tape apparatus further includes a buffer, a reading and writing channel, a head, a motor, reels on which the tape is wound, a read and write controller, a head position controlling system, and a motor driver.

18. The method of claim 16 , further comprising:
deleting information associated with the physically overwritten first data set from an index that includes information associated with the location of the first data set on the tape drive.

19. The method of claim 18 , wherein the index is updated every time when the tape is taken out from the tape apparatus, wherein the tape drive writes data while moving back and forth on wraps of a write region along the longitudinal direction of the tape, wherein the tape is divided into the two partitions from the beginning of the tape to the end of the tape, and wherein the dummy records are a predetermined size, and wherein the two partitions are separated by a protection region configured by two wraps, the method further comprising:
writing, by a user, an index file in an XML format onto the tape, wherein the index file includes a directory name, a file name, a file creation date, and position meta-information, including a position on the medium, a size, and an offset in the file, as the meta-information.

20. The method of claim 14 , further comprising:
receiving a request to read the deleted fi

Assignees

• IBM

Inventors

• Iwanaga Masayuki
• Ohta Yumiko
• Oishi Yutaka

Classifications

• G11B5/024 Primary

  Erasing · CPC title

• G06F16/116 Primary

  Details of conversion of file system types or formats · CPC title

• G11B5/00813

  magnetic tapes · CPC title

• G06F17/30076 Primary

  Physics · mapped topic