Index Writing in a Linear Tape File System

• US 20150161161A1
• Filed: 12/05/2013
• Published: 06/11/2015
• Est. Priority Date: 12/05/2013
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Iwanaga, Masayuki, Ohta, Yumiko, Oishi, Yutaka
• Granted Patent: US 9,348,837 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 16/18 File system types

Abstract

Mechanisms are provided for performing a synchronization operation for synchronizing data to a tape medium. The mechanisms receive a request to perform the synchronization operation on the tape medium and obtain file information from a storage device in response to the request. The mechanisms determine if the file information is associated with a file that has been changed since a last index was written to the tape medium. In response to the file information being determined to be associated with a file that has been changed since a last index was written to the tape medium, the mechanisms add index information corresponding to the file information to a partial index. The partial index comprises index information for files less than a total number of files recorded on the tape medium. The mechanisms write the partial index to the tape medium.

Claims

1. A method, in a data processing system comprising a tape storage device that reads and writes data to a tape medium, for performing a synchronization operation for synchronizing data to the tape medium, the method comprising:

receiving a request to perform the synchronization operation on the tape medium;

obtaining file information from a storage device of the data processing system in response to receiving the request;

determining if the file information is associated with a file that has been changed since a last index was written to the tape medium;

in response to the file information being determined to be associated with a file that has been changed since a last index was written to the tape medium, adding index information corresponding to the file information to a partial index, wherein the partial index comprises index information for files less than a total number of files recorded on the tape medium; and

writing the partial index to the tape medium.

2. The method of claim 1, wherein the synchronization operation is part of an unmount operation for unmounting the tape medium from the tape storage device, and wherein the method further comprises unmounting the tape medium after writing of the partial index to the tape medium.

3. The method of claim 1, wherein the partial index comprises only index information for the file that was changed since the last index was written to the tape medium and does not comprise a full index of all files recorded on the tape medium.

4. The method of claim 1, wherein the partial index comprises index information for files on a same path as the file that was changed since the last index was written to the tape medium.

5. The method of claim 1, wherein the partial index comprises index information for files in a same virtual directory as the file that was changed since the last index was written to the tape medium.

6. The method of claim 1, wherein determining if the file information is associated with a file that has been changed since a last index was written to the tape medium comprises determining if the file information is for a file that is on a same path as the file that has been changed since the last index was written to the tape medium, and wherein adding index information corresponding to the file information to the partial index is performed in response to determining that the file information is for a file that is on a same path as the file that has been changed since the last index was written to the tape medium.

7. The method of claim 1, wherein determining if the file information is associated with a file that has been changed since a last index was written to the tape medium comprises determining if the file information is for a file in a same virtual directory as the file that has been changed since the last index was written to the tape medium, and wherein adding index information corresponding to the file information to the partial index is performed in response to determining that the file information is for a file that is in a same virtual directory as the file that has been changed since the last index was written to the tape medium.

8. The method of claim 1, wherein writing the partial index to the tape medium comprises writing the partial index to both an index partition and a data partition of the tape medium.

9. The method of claim 1, wherein writing the partial index to the tape medium comprises writing the partial index to one of an index partition or a data partition of the tape medium, and wherein a full index comprising index information for all files recorded on the tape medium is written to an other one of the index partition or the data partition of the tape medium.

10. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:

receive a request to perform a synchronization operation on a tape medium;

obtain file information from a storage device of the computing device in response to receiving the request;

determine if the file information is associated with a file that has been changed since a last index was written to the tape medium;

in response to the file information being determined to be associated with a file that has been changed since a last index was written to the tape medium, add index information corresponding to the file information to a partial index, wherein the partial index comprises index information for files less than a total number of files recorded on the tape medium; and

write the partial index to the tape medium.

11. The computer program product of claim 10, wherein the synchronization operation is part of an unmount operation for unmounting the tape medium from the tape storage device, and wherein the computer program product further causes the computing device to unmount the tape medium after writing of the partial index to the tape medium.

12. The computer program product of claim 10, wherein the partial index comprises only index information for the file that was changed since the last index was written to the tape medium and does not comprise a full index of all files recorded on the tape medium.

13. The computer program product of claim 10, wherein the partial index comprises index information for files on a same path as the file that was changed since the last index was written to the tape medium.

14. The computer program product of claim 10, wherein the partial index comprises index information for files in a same virtual directory as the file that was changed since the last index was written to the tape medium.

15. The computer program product of claim 10, wherein the computer program product further causes the computing device to determine if the file information is associated with a file that has been changed since a last index was written to the tape medium at least by determining if the file information is for a file that is on a same path as the file that has been changed since the last index was written to the tape medium, and wherein adding index information corresponding to the file information to the partial index is performed in response to determining that the file information is for a file that is on a same path as the file that has been changed since the last index was written to the tape medium.

16. The computer program product of claim 10, wherein the computer program product further causes the computing device to determine if the file information is associated with a file that has been changed since a last index was written to the tape medium at least by determining if the file information is for a file in a same virtual directory as the file that has been changed since the last index was written to the tape medium, and wherein adding index information corresponding to the file information to the partial index is performed in response to determining that the file information is for a file that is in a same virtual directory as the file that has been changed since the last index was written to the tape medium.

17. The computer program product of claim 10, wherein the computer program product further causes the computing device to write the partial index to the tape medium at least by writing the partial index to both an index partition and a data partition of the tape medium.

18. The computer program product of claim 10, wherein the computer program product further causes the computing device to write the partial index to the tape medium at least by writing the partial index to one of an index partition or a data partition of the tape medium, and wherein a full index comprising index information for all files recorded on the tape medium is written to an other one of the index partition or the data partition of the tape medium.

19. An apparatus, comprising:

a storage device; and

a tape storage device coupled to the storage device, wherein the apparatus comprises logic configured to;

receive a request to perform a synchronization operation on a tape medium of the tape storage device;

obtain file information from the storage device in response to receiving the request;

determine if the file information is associated with a file that has been changed since a last index was written to the tape medium;

in response to the file information being determined to be associated with a file that has been changed since a last index was written to the tape medium, add index information corresponding to the file information to a partial index, wherein the partial index comprises index information for files less than a total number of files recorded on the tape medium; and

write the partial index to the tape medium.

20. A method, in a data processing system comprising a tape storage device that reads and writes data to a tape medium, for mounting the tape medium, the method comprising:

receiving a request to mount the tape medium in the tape storage device, wherein the tape medium comprises at least one full index stored on the tape medium and at least one partial index stored on the tape medium;

identifying a most recent generation index that is a full index stored on the tape medium;

reading first index information from the full index;

iteratively reading second index information from each partial index stored on the tape medium having a generation identifier that is more recent than the most recent generation index that is a full index;

building an index of all files stored on the tape medium from the first index information and second index information; and

mounting the tape medium using the index of all files stored on the tape medium.