Method of managing, writing, and reading file on tape

Patent metadata

Field	Value
Publication number	US-2016012073-A1
Application number	US-201514719344-A
Country	US
Kind code	A1
Filing date	May 22, 2015
Priority date	Jul 11, 2014
Publication date	Jan 14, 2016
Grant date	—

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.

First claim

What is claimed is:

1 . A method for managing a file on a tape in a file system, the method comprising:
in response to a request to write a first file to a tape, detecting whether a second file including data identical to data of the first file already exists on the tape; if the second file exists on the tape, updating a first index of the second file; and in response to completing the write of the first file to the tape, adding metadata, including a data starting position and a size of the first file, to the first index.

2 . The method according to claim 1 , further comprising:
writing the first file onto the tape; and creating or updating a second index with metadata including a data starting position and a size of the first file on the tape.

3 . The method according to claim 2 , further comprising:
writing the updated first index onto the tape; and writing the created or updated second index onto the tape.

4 . The method according to claim 2 , further comprising:
in response to a request to read the first file or the second file, reading the metadata of the first index and the second index; determining, based on the read metadata, which of the first file and the second file can be accessed faster from a current head position; and reading, from the tape, the first file or the second file that can be accessed faster.

5 . A method of writing a file onto a tape in a file system, comprising:
in response to a request to write a first file to a tape, detecting whether a second file including data identical to data of the first file already exists on the tape; writing the first file onto the tape; and if the second file exists on the tape, updating metadata of a first index of the second file to include a data starting position and a size of the first file on the tape.

6 . The method according to claim 5 , wherein the writing the first file onto the tape is executed before the detecting.

7 . The method according to claim 6 , further comprising creating or updating a second index to include metadata including a data starting position and a size of the first file on the tape.

8 . The method according to claim 7 , further comprising:
writing the updated first index onto the tape; and writing the created or updated second index onto the tape.

9 . A method of reading a file from a tape in a file system, comprising:
in response to a request to read a first file from a tape, detecting whether other data identical to data of the first file exists on the tape; if other identical data exists on the tape, determining which of the data of the first file and the other identical data can be accessed faster from a current head position; and reading, from the tape, the data of the first file or the other identical data that can be accessed faster.

10 . The method according to claim 9 , wherein the detecting includes acquiring metadata on the first file, and acquiring metadata on the other identical data.

11 . The method according to claim 10 , wherein the determining includes making the determination based on position information on the tape in the acquired metadata on the data of the file and the identical data.

Assignees

• IBM

Inventors

• Ashida Takashi
• Hasegawa Tohru
• Itagaki Hiroshi
• Mitsuma Machida
• Watanabe Terue

Classifications

• G11B27/328

  on a tape [TTOC] · CPC title

• G11B27/107

  of operating tapes · CPC title

• G11B2020/1265

  Control data, system data or management information, i.e. data used to access or process user data · CPC title

• G11B20/1201 Primary

  on tapes · CPC title

• G11B2020/1295

  wherein the focus is on the read access speed · CPC title