FILE DEDUPLICATION IN A FILE SYSTEM

• US 20120102000A1
• Filed: 09/22/2011
• Published: 04/26/2012
• Est. Priority Date: 10/25/2010
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: TOSAKA, Eiji
• Granted Patent: US 8,812,460 B2
• Time in Patent Office: Days
• US Class Current: 707/654
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 11/1464 for networked environments
• 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 16/162 Delete operations erasing in storage systems G06F3/0652
• CPC Class Codes: G06F 16/1748 De-duplication implemented within the file system, e.g. based on file segments de-duplication techniques in storage systems for the management of data blocks G06F3/0641
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Each file is assigned in advance with a WWUID which is newly assigned to a file upon the creation or update of the file and is inherited from a file to a copied file when the file is copied. In a backup apparatus, a file name reception unit receives the file name of a backup target file. A WWUID reception unit receives a WWUID corresponding to the file name. A WWUID search unit searches for the same WWUID in backup management information of a previous day stored in a backup destination. Only if the search is failed, a file operation instruction unit instructs the storing of the backup target file into the backup destination. Then, an Rcnt update instruction unit instructs the updating of the number of references made to the WWUID within the backup destination. A second management information update instruction unit then instructs the updating of backup management information of the current day.

Claims

1. An apparatus for file deduplication in a file system, comprising:

an acquisition unit configured to acquire identification information which is newly assigned to a file upon creation or update of the file and is inherited by the file from a different file if the file is a copy of the different file, to thereby make a content of the file identifiable;

a determination unit configured to determine whether or not first identification information and second identification information match each other, the first identification information being the identification information acquired by the acquisition unit and assigned to a first file, the second identification information being the identification information acquired by the acquisition unit and assigned to a second file; and

a control unit configured to perform such control that the first file and the second file are prevented from being stored as duplicate files in the file system, if the determination unit determines that the first identification information and the second identification information match each other.

2. The apparatus according to claim 1, wherein

the acquisition unit includes:

a first acquisition unit configured to acquire the first identification information assigned to the first file backed up to the file system at a first time point, from first management information for managing each file backed up to the first system at the first time point; and

a second acquisition unit configured to acquire the second identification information assigned to the second file to be backed up to the file system at a second time point subsequent to the first time point, and

if the determination unit determines that the first identification information and the second identification information match each other, the control unit performs such control that the second file is prevented from being copied to the file system at the second time point and that the second identification information is included in second management information and associated with the first file, the second management information for managing each file backed up at the second time point.

3. The apparatus according to claim 2, further comprising:

a first registration unit configured to register, in count information, an increase in the number of pieces of identification information associated with the first file, when the second identification information becomes associated with the first file, the count information indicating the number of pieces of identification information associated with the first file;

a second registration unit configured to register, in the count information, a decrease in the number of pieces of identification information associated with the first file, in response to an instruction to delete the first management information; and

a deletion unit configured to delete the first management information in response to the instruction to delete the first management information, and to also delete the first file if the count information after the registration by the second registration unit indicates that no identification information is associated with the first file.

4. The apparatus according to claim 1, wherein

the acquisition unit includes:

a first acquisition unit configured to acquire the first identification information assigned to the first file stored in a server computer, from first management information for managing each file stored in the server computer; and

a second acquisition unit configured to acquire the second identification information assigned to the second file stored in a client computer, from second management information for managing each file stored in the client computer, and

the control unit performs such control that the second file is deleted from the client computer, if the determination unit determines that the first identification information and the second identification information match each other.

5. The apparatus according to claim 1, wherein

the acquisition unit includes:

a first acquisition unit configured to acquire the first identification information assigned to the first file stored in a server computer, from management information for managing each file stored in the server computer; and

a second acquisition unit configured to acquire the second identification information from data in an electronic mail received by a client computer, the second identification information being assigned to the second file attached to the electronic mail, and

the control unit performs such control that the second file is prevented from being saved in the client computer, if the determination unit determines that the first identification information and the second identification information match each other.

6. An apparatus for backing up a file to a file system, comprising:

a first acquisition unit configured to acquire first management information for managing each file backed up to the file system at a first time point;

a second acquisition unit configured to acquire backup target file identification information as identification information which is newly assigned to a file upon creation or update of the file and is inherited by the file from a different file if the file is a copy of the different file, to thereby make a content of the file identifiable, and which is assigned to a backup target file to be backed up to the file system at a second time point subsequent to the first time point;

a determination unit configured to determine whether or not the first management information acquired by the first acquisition unit includes the backup target file identification information acquired by the second acquisition unit as already-backed-up file identification information that is the identification information assigned to an already-backed-up file backed up to the file system at the first time point;

a copy unit configured to prevent the backup target file from being copied to the file system at the second time point if the determination unit determines that the first management information includes the backup target file identification information, and configured to copy the backup target file to the file system at the second time point if the determination unit determines that the first management information does not include the backup target file identification information;

a storage unit configured to store the backup target file identification information in association with the already-backed-up file into second management information for managing each file backed up at the second time point;

a first registration unit configured to register, in count information, an increase in the number of pieces of identification information associated with the already-backed-up file, when the backup target file identification information becomes associated with the already-backed-up file, the count information indicating the number of pieces of identification information associated with the already-backed-up file;

a second registration unit configured to register, in the count information, a decrease in the number of pieces of identification information associated with the already-backed-up file, in response to an instruction to delete the first management information; and

a deletion unit configured to delete the backup target file identification information in response to the instruction to delete the first management information, and to also delete the already-backed-up file if the count information after the registration by the second registration unit indicates that no identification information is associated with the already-backed-up file.

7. An apparatus for managing a file in a file system, comprising:

a first assignment unit configured to assign identification information to a new file when the new file is crated in the file system;

a second assignment unit configured to assign identification information same as the identification information to a copied file when the new file is copied to generate the copied file in the file system; and

a third assignment unit configured to assign identification information different from the identification information to an updated file when any one of the new file and the copied file is updated to generate the updated file.

8. The apparatus according to claim 7, further comprising an addition unit configured to, when a given file is changed in the file system, add the identification information assigned to the given file to a file that is different from the given file and indicative of a content of the change.

9. A method for file deduplication in a file system by a processor, comprising:

acquiring identification information which is newly assigned to a file upon creation or update of the file and is inherited by the file from a different file if the file is a copy of the different file, to thereby make a content of the file identifiable;

determining whether or not first identification information and second identification information match each other, the first identification information being the identification information acquired by the acquisition unit and assigned to a first file, the second identification information being the identification information acquired by the acquisition unit and assigned to a second file; and

if the first identification information is determined to match the second identification information, preventing the first file and the second file from being stored as duplicate files in the file system.

10. The method according to claim 9, further comprising:

acquiring the first identification information assigned to the first file backed up to the file system at a first time point, from first management information for managing each file backed up to the first system at the first time point; and

acquiring the second identification information assigned to the second file to be backed up to the file system at a second time point subsequent to the first time point, and

if the first identification information and the second identification information match each other, preventing the first and second identification information from being copied to the file system at the second time point and that the second identification information is included in second management information and associated with the first file, the second management information for managing each file backed up at the second time point.

11. The method according to claim 10, further comprising:

registering, in count information, an increase in the number of pieces of identification information associated with the first file, when the second identification information becomes associated with the first file, the count information indicating the number of pieces of identification information associated with the first file;

registering, in the count information, a decrease in the number of pieces of identification information associated with the first file, in response to an instruction to delete the first management information; and

deleting the first management information in response to the instruction to delete the first management information, and to also delete the first file if the count information after the registration by the second registration unit indicates that no identification information is associated with the first file.

12. The method according to claim 9, further comprising

acquiring the first identification information assigned to the first file stored in a server computer, from first management information for managing each file stored in the server computer,

acquiring the second identification information assigned to the second file stored in a client computer, from second management information for managing each file stored in the client computer, and

if the first identification information and the second identification information match each other, deleting the second file from the client computer.

13. The method according to claim 9, further comprising:

acquiring the first identification information assigned to the first file stored in a server computer, from management information for managing each file stored in the server computer; and

acquiring the second identification information from data in an electronic mail received by a client computer, the second identification information being assigned to the second file attached to the electronic mail, and

if the first identification and the second identification match each other, preventing the second file from being saved in the client computer.

14. A computer program product for file deduplication in a file system by a processor, the computer program product comprising a non-transitory computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

a first executable portion for acquiring identification information which is newly assigned to a file upon creation or update of the file and is inherited by the file from a different file if the file is a copy of the different file, to thereby make a content of the file identifiable;

a second executable portion for determining whether or not first identification information and second identification information match each other, the first identification information being the identification information acquired by the acquisition unit and assigned to a first file, the second identification information being the identification information acquired by the acquisition unit and assigned to a second file; and

a third executable portion for, if the first identification information is determined to match the second identification information, preventing the first file and the second file from being stored as duplicate files in the file system.

15. The computer program product according to claim 14, further comprising:

a fourth executable portion for acquiring the first identification information assigned to the first file backed up to the file system at a first time point, from first management information for managing each file backed up to the first system at the first time point; and

a fifth executable portion for acquiring the second identification information assigned to the second file to be backed up to the file system at a second time point subsequent to the first time point, and

a sixth executable portion for, if the first identification information and the second identification information match each other, preventing the first and second identification information from being copied to the file system at the second time point and that the second identification information is included in second management information and associated with the first file, the second management information for managing each file backed up at the second time point.

16. The computer program product according to claim 15, further comprising:

a seventh executable portion for registering, in count information, an increase in the number of pieces of identification information associated with the first file, when the second identification information becomes associated with the first file, the count information indicating the number of pieces of identification information associated with the first file;

an eighth executable portion for registering, in the count information, a decrease in the number of pieces of identification information associated with the first file, in response to an instruction to delete the first management information; and

a ninth executable portion for deleting the first management information in response to the instruction to delete the first management information, and to also delete the first file if the count information after the registration by the second registration unit indicates that no identification information is associated with the first file.

17. The computer program product according to claim 14, further comprising

a fourth executable portion for acquiring the first identification information assigned to the first file stored in a server computer, from first management information for managing each file stored in the server computer,

a fifth executable portion for acquiring the second identification information assigned to the second file stored in a client computer, from second management information for managing each file stored in the client computer, and

a sixth executable portion for, if the first identification information and the second identification information match each other, deleting the second file from the client computer.

18. The computer program product according to claim 14, further comprising:

a fourth executable portion for acquiring the first identification information assigned to the first file stored in a server computer, from management information for managing each file stored in the server computer; and

a fifth executable portion for acquiring the second identification information from data in an electronic mail received by a client computer, the second identification information being assigned to the second file attached to the electronic mail, and

a sixth executable portion for, if the first identification and the second identification match each other, preventing the second file from being saved in the client computer.