Method of managing, writing, and reading file on tape

• US 9,852,756 B2
• Filed: 01/13/2017
• Issued: 12/26/2017
• Est. Priority Date: 07/11/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ashida, Takashi, Hasegawa, Tohru, Itagaki, Hiroshi, Mitsuma, Shinsuke, Watanabe, Terue
• Primary Examiner(s): Young, Wayne
• Assistant Examiner(s): HABERMEHL, JAMES LEE
• Application Number:
  US15/405,667
• Publication Number:
  US 20170125061A1
• Time in Patent Office: 347 Days
• Field of Search: 360 31, 360 48, 360 53, 360 55, 360 69, 360 71, 360 721- 722
• CPC Class Codes: G11B 20/1201 on tapes
• CPC Class Codes: G11B 2020/1265 Control data, system data or management information, i.e. data used to access or process user data
• CPC Class Codes: G11B 2020/1295 wherein the focus is on the read access speed
• CPC Class Codes: G11B 27/107 of operating tapes
• CPC Class Codes: G11B 27/328 on a tape [TTOC]

Abstract

Managing a file on a tape. In response to a request to write a first file to a tape, whether a second file including data identical to the first file already exists on the tape is detected. If the second file exists, a first index of the second file is updated. After completing the write of the first file, metadata, including data starting position and size of the first file, is added to the first index. In response to a request to read the first or second files, the metadata of the first and second indexes are read. Based on the metadata, which of the first or second files can be accessed faster from a current head position is determined. The first file or the second file that can be accessed faster is then read from the tape.

Claims

1. A file system including a tape drive, comprising:

means for, when a file is to be written onto the tape, detecting, using software which has a detection function for duplicate data, whether another file including data identical to data of the file already exists on the tape;

means for, when the other file exists on the tape, updating a first index of the other file;

means for, after the file is written, adding meta-information including a data starting position and a size of the written file on the tape to the first index and writing in an index partition;

means for creating or updating a second index including meta-information including a data starting position and a size of the written file on the tape; and

means for writing the created or updated second index in an index partition on the tape.

2. The file system according to claim 1, further comprising:

means for, writing the file onto the tape before the detecting.

3. The file system according to claim 1, further comprising:

means for, when the file or the other file on the tape is to be read, acquiring the meta-information of the first index and the second index from an index partition on the tape;

means for determining which of the file and the other file can be read faster based on the starting positions of the file and the other file from the acquired meta-information and a current head position; and

means for reading, from the tape, the file or the other file that can be read faster.