Increasing data storage capacity by reducing index entries

• US 10,453,485 B1
• Filed: 11/26/2018
• Issued: 10/22/2019
• Est. Priority Date: 11/26/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Miyamura, Tsuyoshi, Itagaki, Hiroshi, Hasegawa, Tohru, Yamamoto, Noriko, Mitsuma, Shinsuke, Matsui, Sosuke
• Primary Examiner(s): Hindi, Nabil Z
• Application Number:
  US16/200,391
• Time in Patent Office: 330 Days
• Field of Search: 360 48, 360 721, 360 7304, 360 7403, 360 75, 360 7712
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G11B 20/1201 on tapes
• CPC Class Codes: G11B 27/032 on tapes G11B27/036, G11B27/038 take precedence
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/309 Table of contents
• CPC Class Codes: G11B 5/00821 using stationary heads
• CPC Class Codes: G11B 5/5504 across tape tracks

Abstract

A tape method, according to one embodiment, includes: adjusting a position of a tape head in the tape drive relative to a magnetic tape such that the tape head is positioned at an accumulating backhitchless flush (ABF) wrap on the magnetic tape. A first index is also written in the ABF wrap. The first index corresponds to data written in a data partition on the magnetic tape, and the ABF wrap and the data partition are different partitions. Furthermore, in response to writing the first index in the ABF wrap, the position of the tape head is adjusted relative to the magnetic tape such that the tape head is positioned at the data partition. A first empty index is also appended to an end of the data written in the data partition, where a size of the first empty index is less than a size of the first index.

Claims

1. A tape drive-implemented method, comprising:

in response to detecting a first lapse of a predetermined amount of time, adjusting a position of a tape head in the tape drive relative to a magnetic tape such that the tape head is positioned at an accumulating backhitchless flush (ABF) wrap on the magnetic tape;

writing a first index in the ABF wrap, wherein the first index corresponds to data written in a data partition on the magnetic tape, wherein the ABF wrap and the data partition are different partitions;

in response to writing the first index in the ABF wrap, adjusting the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

appending a first empty index to an end of the data written in the data partition, wherein a size of the first empty index is less than a size of the first index.

2. The tape drive-implemented method of claim 1, wherein the first empty index includes:

a first beginning file mark;

a first closing file mark; and

a first end of record sandwiched between the first beginning file mark and the first closing file mark,

wherein the first end of record corresponds to the first index in the ABF wrap.

3. The tape drive-implemented method of claim 1, comprising:

detecting a second lapse of the predetermined amount of time;

in response to detecting the second lapse, adjusting the position of the tape head relative to the magnetic tape such that the tape head is positioned at the ABF wrap on the magnetic tape;

writing a second index in the ABF wrap, wherein the second index corresponds to data written in the data partition after the first empty index;

invalidating the first index in the ABF wrap;

in response to writing the second index in the ABF wrap, adjusting the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

appending a second empty index to an end of the data written in the data partition after the first empty index, wherein a size of the second empty index is less than a size of the second index.

4. The tape drive-implemented method of claim 3, wherein the second empty index includes:

a second beginning file mark;

a second closing file mark; and

a second end of record sandwiched between the second beginning file mark and the second closing file mark,

wherein the second end of record corresponds to the second index in the ABF wrap.

5. The tape drive-implemented method of claim 3, comprising:

in response to receiving an unmount command, reading the second index from the ABF wrap;

using the second index to overwrite the second empty index;

invalidating the second index in the ABF wrap;

copying the second index in an index partition on the magnetic tape; and

satisfying the unmount command.

6. The tape drive-implemented method of claim 3, comprising:

in response to experiencing a disaster situation, using the second index in the ABF wrap to restore a file system of the data written in the data partition.

7. The tape drive-implemented method of claim 3, comprising:

in response to receiving an unmount command before appending the second empty index to the end of the data written in the data partition after the first empty index, generating the second index;

appending the second index to the end of the data written in the data partition after the first empty index;

invalidating the first index in the ABF wrap;

copying the second index in the index partition; and

satisfying the unmount command.

8. The tape drive-implemented method of claim 1, wherein the ABF wrap and the data partition are different data partitions in a same data band on the magnetic tape, wherein the ABF wrap is eventually used as a data partition to store data.

9. A computer program product comprising a computer readable storage medium having program instructions embodied therewith, the program instructions readable and/or executable by a processor to cause the processor to:

in response to detecting a first lapse of a predetermined amount of time, adjust, by the processor, a position of a tape head in a tape drive relative to a magnetic tape such that the tape head is positioned at an accumulating backhitchless flush (ABF) wrap on the magnetic tape;

write, by the processor, a first index in the ABF wrap, wherein the first index corresponds to data written in a data partition on the magnetic tape, wherein the ABF wrap and the data partition are different partitions;

in response to writing the first index in the ABF wrap, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

append, by the processor, a first empty index to an end of the data written in the data partition, wherein a size of the first empty index is less than a size of the first index.

10. The computer program product of claim 9, wherein the first empty index includes:

a first beginning file mark;

a first closing file mark; and

a first end of record sandwiched between the first beginning file mark and the first closing file mark,

wherein the first end of record corresponds to the first index in the ABF wrap.

11. The computer program product of claim 9, the program instructions readable and/or executable by the processor to cause the processor to:

detect, by the processor, a second lapse of the predetermined amount of time;

in response to detecting the second lapse, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the ABF wrap on the magnetic tape;

write, by the processor, a second index in the ABF wrap, wherein the second index corresponds to data written in the data partition after the first empty index;

invalidate, by the processor, the first index in the ABF wrap;

in response to writing the second index in the ABF wrap, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

append, by the processor, a second empty index to an end of the data written in the data partition after the first empty index, wherein a size of the second empty index is less than a size of the second index.

12. The computer program product of claim 11, wherein the second empty index includes:

a second beginning file mark;

a second closing file mark; and

a second end of record sandwiched between the second beginning file mark and the second closing file mark,

wherein the second end of record corresponds to the second index in the ABF wrap.

13. The computer program product of claim 11, the program instructions readable and/or executable by the processor to cause the processor to:

in response to receiving an unmount command, read, by the processor, the second index from the ABF wrap;

use, by the processor, the second index to overwrite the second empty index;

invalidate, by the processor, the second index in the ABF wrap;

copy, by the processor, the second index in an index partition on the magnetic tape; and

satisfy, by the processor, the unmount command.

14. The computer program product of claim 11, the program instructions readable and/or executable by the processor to cause the processor to:

in response to experiencing a disaster situation, use, by the processor, the second index in the ABF wrap to restore a file system of the data written in the data partition.

15. The computer program product of claim 11, the program instructions readable and/or executable by the processor to cause the processor to:

in response to receiving an unmount command before appending the second empty index to the end of the data written in the data partition after the first empty index, generate, by the processor, the second index;

append, by the processor, the second index to the end of the data written in the data partition after the first empty index;

invalidate, by the processor, the first index in the ABF wrap;

copy, by the processor, the second index in the index partition; and

satisfy, by the processor, the unmount command.

16. The computer program product of claim 9, wherein the ABF wrap and the data partition are different data partitions in a same data band on the magnetic tape, wherein the ABF wrap is eventually used as a data partition to store data.

17. A system, comprising:

a tape drive;

a processor; and

logic integrated with the processor, executable by the processor, or integrated with and executable by the processor, the logic being configured to;

in response to detecting a first lapse of a predetermined amount of time, adjust, by the processor, a position of a tape head in a tape drive relative to a magnetic tape such that the tape head is positioned at an accumulating backhitchless flush (ABF) wrap on the magnetic tape;

write, by the processor, a first index in the ABF wrap, wherein the first index corresponds to data written in a data partition on the magnetic tape, wherein the ABF wrap and the data partition are different partitions;

in response to writing the first index in the ABF wrap, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

append, by the processor, a first empty index to an end of the data written in the data partition, wherein a size of the first empty index is less than a size of the first index.

18. The system of claim 17, the logic being configured to:

detecting, by the processor, a second lapse of the predetermined amount of time;

in response to detecting the second lapse, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the ABF wrap on the magnetic tape;

write, by the processor, a second index in the ABF wrap, wherein the second index corresponds to data written in the data partition after the first empty index;

invalidate, by the processor, the first index in the ABF wrap;

in response to writing the second index in the ABF wrap, adjust, by the processor, the position of the tape head relative to the magnetic tape such that the tape head is positioned at the data partition; and

append, by the processor, a second empty index to an end of the data written in the data partition after the first empty index, wherein a size of the second empty index is less than a size of the second index.

19. The system of claim 18, the logic being configured to:

in response to receiving an unmount command, read, by the processor, the second index from the ABF wrap;

use, by the processor, the second index to overwrite the second empty index;

invalidate, by the processor, the second index in the ABF wrap;

copy, by the processor, the second index in an index partition on the magnetic tape; and

satisfy, by the processor, the unmount command.

20. The system of claim 18, the logic being configured to:

in response to receiving an unmount command before appending the second empty index to the end of the data written in the data partition after the first empty index, generate, by the processor, the second index;

append, by the processor, the second index to the end of the data written in the data partition after the first empty index;

invalidate, by the processor, the first index in the ABF wrap;

copy, by the processor, the second index in the index partition; and

satisfy, by the processor, the unmount command.