FILE SYSTEM FOR ROLLING BACK DATA ON TAPE

• US 20160092315A1
• Filed: 08/10/2015
• Published: 03/31/2016
• Est. Priority Date: 09/29/2014
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ashida, Takashi, Itagaki, Hiroshi, Masuda, Setsuko, Miyamura, Tsuyoshi, Watanabe, Terue
• Granted Patent: US 9,886,355 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 16/13 File access structures, e.g. distributed indices arrangements of input from, or output to, record carriers G06F3/06
• CPC Class Codes: G06F 16/1805 Append-only file systems, e.g. using logs or journals to store data
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0682 Tape device
• CPC Class Codes: G06F 3/0686 Libraries, e.g. tape libraries, jukebox
• CPC Class Codes: G06Q 10/00 Administration; Management

Abstract

Rolling back data on tape in a file system is provided. A management tape is prepared. The management tape has only index files recorded thereon. The index files contain information about start positions and lengths of corresponding data files recorded on normal tapes. The index files further contain identification information for the normal tapes. A first index file of the management tape is read. The first index file is related to a data file to be rolled back. The first index file is read out from the management tape mounted on a first tape drive. The data file to be rolled back is read out of a first normal tape. The first normal tape is identified based on information in the first index file. The first normal tape is mounted on a second tape drive.

Claims

1. A method for rolling back data on tape in a file system, the method comprising:

preparing a management tape with only index files recorded thereon, the index files containing information about start positions and lengths of corresponding data files recorded on normal tapes, and the index files further containing identification information for the normal tapes;

reading a first index file of the management tape, wherein the first index file is related to a data file to be rolled back, wherein the first index file is read out from the management tape mounted on a first tape drive; and

reading the data file to be rolled back out of a first normal tape, wherein the first normal tape is identified based on information in the first index file, and wherein the first normal tape is mounted on a second tape drive.

2. The method according to claim 1, further comprising:

adding an updated index file to the management tape with a predetermined timing, wherein the updated index file is generated each time a data file recorded on the normal tapes is updated.

3. The method according to claim 2, wherein:

the management tape includes a plurality of partitions, each of the plurality of partitions corresponding to a normal tape of the normal tapes; and

the updated index file is added to a partition of the plurality of partitions that corresponds to the normal tape on which the updated data file is recorded.

4. The method according to claim 2, wherein the management tape includes a data partition and an index partition, and wherein adding the updated index file to the management tape includes adding the updated index file to the data partition.

5. The method according to claim 1, wherein the first tape drive is not the same tape drive as the second tape drive.

6. The method according to claim 1, wherein the first tape drive is the same tape drive as the second tape drive.

7. A file system which allows data on tape to be rolled back using a management tape, the file system comprising:

a host;

a first tape drive adapted to mount normal tapes with data files recorded thereon; and

a second tape drive adapted to mount a management tape with only index files recorded thereon, the index files containing information about start positions and lengths of corresponding data files recorded on the normal tapes and the index files further containing identification information about the normal tapes, wherein

the host reads the index file related to a data file to be rolled back out, wherein the index file is read back out of the management tape mounted on the second tape drive, and the host reads the data file to be rolled back out of the normal tape identified based on information in the index file, the normal tape being mounted on the first tape drive.

8. The file system according to claim 7, wherein the host adds an updated index file to the management tape with a predetermined timing, wherein the updated index file is generated each time a data file recorded on the normal tapes is updated.

9. The file system according to claim 8, wherein:

the management tape includes a plurality of partitions, each of the plurality of partitions corresponding; and

the host adds the updated index file to a partition of the plurality of partitions that corresponds to the normal tape on which the updated data file is recorded.

10. The file system according to claim 8, wherein the management tape includes a data partition and an index partition, and wherein the host adds the updated index file to the data partition.

11. A computer program product for rolling back data on tape in a file system, the program being stored on non-transitory computer readable storage media and controlling a computer to perform a method, the method comprising:

preparing a management tape with only index files recorded thereon, the index files containing information about start positions and lengths of corresponding data files recorded on normal tapes, and the index files further containing identification information for the normal tapes;

reading a first index file of the management tape, wherein the first index file is related to a data file to be rolled back, wherein the first index file is read out from the management tape mounted on a first tape drive; and

reading the data file to be rolled back out of a first normal tape, wherein the first normal tape is identified based on information in the first index file, and wherein the first normal tape is mounted on a second tape drive.

12. The computer program product of claim 11, wherein the method further comprises:

adding an updated index file to the management tape with a predetermined timing, wherein the updated index file is generated each time a data file recorded on the normal tapes is updated.

13. The computer program product of claim 12, wherein:

the management tape includes a plurality of partitions, each of the plurality of partitions corresponding to a normal tape of the normal tapes; and

the updated index file is added to a partition of the plurality of partitions that corresponds to the normal tape on which the updated data file is recorded.

14. The computer program product of claim 12, wherein the management tape includes a data partition and an index partition, and wherein adding the updated index file to the management tape includes adding the updated index file to the data partition.

15. The computer program product of claim 11, wherein the first tape drive is not the same tape drive as the second tape drive.

16. The computer program product of claim 11, wherein the first tape drive is the same tape drive as the second tape drive.