Columnar data storage on tape partition

• US 9,595,291 B1
• Filed: 04/27/2016
• Issued: 03/14/2017
• Est. Priority Date: 04/27/2016
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kawamura, Kousei, Matsui, Sosuke, Masuda, Koichi, Oishi, Yutaka, Tsuda, Takahiro
• Primary Examiner(s): Hindi, Nabil
• Application Number:
  US15/139,384
• Time in Patent Office: 321 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/221 Column-oriented storage; Management thereof
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G11B 20/1201 on tapes
• CPC Class Codes: G11B 2020/1295 wherein the focus is on the read access speed
• CPC Class Codes: G11B 2220/95 Serpentine format, wherein a single track or group of tracks traverses the tape plural times from one end to the other
• 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 5/00817 on longitudinal tracks only, e.g. for serpentine format recording

Abstract

A method for writing data from a table to a tape includes setting a number of partitions on the tape, where the number of partitions is greater than or equal to a number of columns of the table to be written to the tape, and writing data from each column of the table to at least one partition of the tape, the at least one partition including two or more wraps, the data is written from a top of the two or more wraps towards a bottom of the two or more wraps in a direction of a width of the at least one partition. The written data is reciprocated from a beginning of the tape to an end of the tape in a longitudinal direction of the tape such that writing of a last data entry of one column ends at a beginning of the two or more wraps.

Claims

1. A method for writing data from a table to a tape, the method comprising:

setting a number of partitions on the tape, wherein the number of partitions is greater than or equal to a number of columns of the table to be written to the tape; and

writing data from each column of the table to at least one partition of the tape, the at least one partition comprising two or more wraps, the data is written from a top of the two or more wraps towards a bottom of the two or more wraps in a direction of a width of the at least one partition,

wherein the written data is reciprocated from a beginning of the tape to an end of the tape in a longitudinal direction of the tape such that writing of a last data entry of one column ends at a beginning of a 2n^th wrap of the two or more wraps.

2. The method of claim 1, further comprising:

writing half of a remaining portion of the data to be written to the tape in one column from a beginning of a (2n−

1)^th wrap; and

writing another half of the remaining portion of the data to be written to the tape from a position of the 2n^th wrap located directly below a last position of the (2n−

1)^th wrap to the beginning of the 2n^th wrap.

3. The method of claim 1, wherein the table comprises at least two or more columns and at least two or more rows.

4. The method of claim 1, wherein a number of wraps in the at least one partition is determined according to a size of a corresponding column to be written.

5. A method for setting partitions on a tape, the method comprising:

obtaining a data size S1 of a column to be written to the tape; and

dividing the data size S1 of the column by a data size S2 of a wrap of the tape to obtain a quotient N, wherein a result of the quotient N is rounded down using a ROUNDDOWN function.

6. The method of claim 5, wherein data from the column is written to a (N+1) wrap of a partition of the tape when the quotient N is an odd number.

7. The method of claim 5, wherein data from the column is written to a (N+2) wrap of a partition of the tape when the quotient N is an even number.

8. The method of claim 6, wherein writing data from the column to a (N+1) wrap of the partition of the tape when the quotient N is an odd number further comprises:

setting a first area extending from a beginning of a N^th wrap to a data size (S1−

(N−

1)*S2)/2 as a data writing area in the partition; and

setting a second area from a position of a (N+1)^th wrap directly below a last position of the data size (S1−

(N−

1)*S2)/2 to be written in the N^th wrap to a beginning of the (N+1)^th wrap as data writing area in the partition comprising the data size (S1−

(N−

1)*S2)/2.

9. The method of claim 7, wherein writing data from the column to a (N+2) wrap of the partition of the tape when the quotient N is an even number further comprises:

setting a third area from the beginning of the (N+1)^th wrap to a data size (S1−

N*S2)/2 as writing data area in the partition; and

setting a fourth area from a position of a (N+2)^th wrap directly below a last position of the data size (S1−

N*S2)/2 to be written in the (N+1)^th wrap to a beginning of the (N+2)^th wrap as a data writing area comprising the data size (S1−

N*S2)/2.

10. A storage system for managing files using a file system comprising:

a host; and

at least one tape drive capable of communicating with the host and executing the file system, the tape drive being controlled by the file system to write data from a table to a tape, wherein the tape drive is capable of performing a method comprising;

setting a number of partitions on the tape, wherein the number of partitions is greater than or equal to a number of columns of the table to be written to the tape; and

writing data from each column of the table to at least one partition of the tape, the at least one partition comprising two or more wraps, the data is written from a top of the two or more wraps towards a bottom of the two or more wraps in a direction of a width of the at least one partition,

wherein the written data is reciprocated from a beginning of the tape to an end of the tape in a longitudinal direction of the tape such that writing of a last data entry of one column ends at a beginning of a 2n^th wrap of the two or more wraps.

11. The storage system of claim 10, further comprising:

writing half of a remaining portion of the data to be written to the tape in one column from a beginning of a (2n−

1)^th wrap; and

writing another half of the remaining portion of the data to be written to the tape from a position of the 2n^th wrap located directly below a last position of the (2n−

1)^th wrap to the beginning of the 2n^th wrap.

12. The storage system of claim 10, wherein the table comprises at least two or more columns and at least two or more rows.

13. The storage system of claim 10, wherein a number of wraps in the at least one partition is determined according to a size of a corresponding column to be written.

14. The storage system of claim 10, further comprising:

obtaining a data size S1 of at least one column to be written to the tape; and

dividing the data size S1 of the at least one column by a data size S2 of at least one wrap of the tape to obtain a quotient N.

15. The storage system of claim 14, wherein a result of the quotient N is rounded down using a ROUNDDOWN function.

16. The storage system of claim 14, wherein data from the at least one column is written to a (N+1) wrap of a partition of the tape when the quotient N is an odd number.

17. The storage system of claim 14, wherein data from the at least one column is written to a (N+2) wrap of a partition of the tape when the quotient N is an even number.