Method, device, and computer program product for storage management

1. A method for storage management, comprising:

obtaining time information related to a removal time point for a backup storage system, the time information indicating that a chunk in the backup storage system whose expiration time does not exceed the removal time point is to be removed;

determining, from a removal period list, a target removal period whose end time does not exceed the removal time point, each removal period in the removal period list being mapped to at least one chunk element, the at least one chunk element representing at least one chunk in the backup storage system whose expiration time is within the removal period to which the at least one chunk element is mapped;

determining at least one target chunk element to which the target removal period is mapped; and

removing, from the backup storage system, at least one target chunk corresponding to the at least one target chunk element.

2. The method of claim 1 , further comprising:

in accordance with a determination that the at least one target chunk is removed, removing the target removal period and the at least one target chunk element.

3. The method of claim 2 , further comprising:

in accordance with a determination that the target removal period and the at least one target chunk element are removed, dividing a removal-period-to-be-divided in the removal period list into at least a first removal period and a second removal period;

dividing at least one chunk element, to which the removal-period-to-be-divided is mapped, into a first group of chunk elements and a second group of chunk elements, an expiration time of a chunk in the backup storage system represented by the first group of chunk elements falling in the first removal period, an expiration time of a chunk in the backup storage system represented by the second group of chunk elements falling in the second removal period; and

mapping the first group of chunk elements to the first removal period and mapping the second group of chunk elements to the second removal period.

4. The method of claim 1 , further comprising:

obtaining identification indicating an expiration time of a newly-created chunk in the backup storage system;

determining a removal-period-to-be-mapped for the newly-created chunk based on the expiration time of the newly-created chunk, the expiration time of the newly-created chunk falling in the removal-period-to-be-mapped, the removal-period-to-be-mapped being included in the removal period list;

generating a chunk element representing the newly-created chunk based on at least the identification and the expiration time of the newly-created chunk; and

mapping the chunk element representing the newly-created chunk to the removal-period-to-be-mapped.

5. The method of claim 4 , wherein generating the chunk element representing the newly-created chunk further comprises:

determining a type of the newly-created chunk and a storage location for storing the chunk element representing the newly-created chunk; and

generating a chunk element representing the newly-created chunk based on the type and the storage location.

6. The method of claim 5 , wherein the type of the newly-created chunk is selected from the following type group:

a directory-composite chunk type used to store directory information of backup data in the backup storage system;

a data chunk type used to store the backup data; and

an index-composite chunk type used to store an index of the data chunk type.

7. The method of claim 1 , further comprising:

obtaining original expiration time, updated expiration time and identification of an updated chunk in the backup storage system;

determining, based on the original expiration time and from the removal period list, an original removal period in which the original expiration time falls;

determining, based on the identification of the updated chunk, a chunk element representing the updated chunk from at least one chunk element to which the original removal period is mapped;

determining, from the removal period list, a target updated removal period in which the updated expiration time falls; and

mapping a chunk element representing the updated chunk to the target updated removal period.

8. A device for storage management, comprising:

at least one processing unit;

at least one memory coupled to the at least one processing unit and storing instructions for execution by the at least one processing unit, the instructions, when executed by the at least one processing unit, causing the device to perform operations , the operations comprising:

obtaining time information related to a removal time point for a backup storage system, the time information indicating that a chunk in the backup storage system whose expiration time does not exceed the removal time point is to be removed;

determining, from a removal period list, a target removal period whose end time does not exceed the removal time point, each removal period in the removal period list being mapped to at least one chunk element, the at least one chunk element representing at least one chunk in the backup storage system whose expiration time is within the removal period to which the at least one chunk element is mapped;

determining at least one target chunk element to which the target removal period is mapped; and

removing, from the backup storage system, at least one target chunk corresponding to the at least one target chunk element.

9. The device of claim 8 , wherein the operations further comprise:

in accordance with a determination that the at least one target chunk is removed, removing the target removal period and the at least one target chunk element.

10. The device of claim 9 , wherein the operations further comprise:

in accordance with a determination that the target removal period and the at least one target chunk element are removed, dividing a removal-period-to-be-divided in the removal period list into at least a first removal period and a second removal period;

dividing at least one chunk element, to which the removal-period-to-be-divided is mapped, into a first group of chunk elements and a second group of chunk elements, an expiration time of a chunk in the backup storage system represented by the first group of chunk elements falling in the first removal period, an expiration time of a chunk in the backup storage system represented by the second group of chunk elements falling in the second removal period; and

mapping the first group of chunk elements to the first removal period and mapping the second group of chunk elements to the second removal period.

11. The device of claim 8 , wherein the operations further comprise:

obtaining identification indicating an expiration time of a newly created chunk in the backup storage system;

determining a removal-period-to-be-mapped for the newly-created chunk based on the expiration time of the newly-created chunk, the expiration time of the newly-created chunk falling in the removal-period-to-be-mapped, the removal-period-to-be-mapped being included in the removal period list;

generating a chunk element representing the newly created chunk based on at least the identification and the expiration time of the newly created chunk; and

mapping the chunk element representing the newly created chunk to the removal-period-to-be-mapped.

12. The device of claim 11 , wherein generating the chunk element representing the newly created chunk further comprises:

determining a type of the newly created chunk and a storage location for storing the chunk element representing the newly created chunk; and

generating a chunk element representing the newly created chunk based on the type and the storage location.

13. The device of claim 12 , wherein the type of the newly created chunk is selected from the following type group:

a directory-composite chunk type used to store directory information of backup data in the backup storage system;

a data chunk type used to store the backup data; and

an index-composite chunk type used to store an index of the data chunk type.

14. The device of claim 8 , wherein the operations further comprise:

obtaining original expiration time, updated expiration time and identification of an updated chunk in the backup storage system;

determining, based on the original expiration time and from the removal period list, an original removal period in which the original expiration time falls;

determining, based on the identification of the updated chunk, a chunk element representing the updated chunk from at least one chunk element to which the original removal period is mapped;

determining, from the removal period list, a target updated removal period in which the updated expiration time falls; and

mapping a chunk element representing the updated chunk to the target updated removal period.

15. A computer program product tangibly stored on a non-transitory computer-readable medium and comprising machine-executable instructions that, when executed, cause a machine to perform operations, the operations comprising:

obtaining time information related to a removal time point for a backup storage system, the time information indicating that a chunk in the backup storage system whose expiration time does not exceed the removal time point is to be removed;

determining, from a removal period list, a target removal period whose end time does not exceed the removal time point, each removal period in the removal period list being mapped to at least one chunk element, the at least one chunk element representing at least one chunk in the backup storage system whose expiration time is within the removal period to which the at least one chunk element is mapped;

determining at least one target chunk element to which the target removal period is mapped; and

removing, from the backup storage system, at least one target chunk corresponding to the at least one target chunk element.

16. The computer program product of claim 15 , wherein the operations further comprise:

in accordance with a determination that the at least one target chunk is removed, removing the target removal period and the at least one target chunk element.

17. The computer program product of claim 16 , wherein the operations further comprise:

in accordance with a determination that the target removal period and the at least one target chunk element are removed, dividing a removal-period-to-be-divided in the removal period list into at least a first removal period and a second removal period;

dividing at least one chunk element, to which the removal-period-to-be-divided is mapped, into a first group of chunk elements and a second group of chunk elements, an expiration time of a chunk in the backup storage system represented by the first group of chunk elements falling in the first removal period, an expiration time of a chunk in the backup storage system represented by the second group of chunk elements falling in the second removal period; and

mapping the first group of chunk elements to the first removal period and mapping the second group of chunk elements to the second removal period.

18. The computer program product of claim 15 , wherein the operations further comprise:

obtaining identification indicating an expiration time of a newly created chunk in the backup storage system;

determining a removal-period-to-be-mapped for the newly-created chunk based on the expiration time of the newly-created chunk, the expiration time of the newly-created chunk falling in the removal-period-to-be-mapped, the removal-period-to-be-mapped being included in the removal period list;

generating a chunk element representing the newly created chunk based on at least the identification and the expiration time of the newly created chunk; and

mapping the chunk element representing the newly created chunk to the removal-period-to-be-mapped.

19. The computer program product of claim 18 , wherein generating the chunk element representing the newly created chunk further comprises:

determining a type of the newly created chunk and a storage location for storing the chunk element representing the newly created chunk; and

generating a chunk element representing the newly created chunk based on the type and the storage location.

20. The computer program product of claim 19 , wherein the type of the newly created chunk is selected from the following type group:

a directory-composite chunk type used to store directory information of backup data in the backup storage system;

a data chunk type used to store the backup data; and

an index-composite chunk type used to store an index of the data chunk type.

21. The computer program product of claim 15 , wherein the operations further comprise:

obtaining original expiration time, updated expiration time and identification of an updated chunk in the backup storage system;

determining, based on the original expiration time and from the removal period list, an original removal period in which the original expiration time falls;

determining, based on the identification of the updated chunk, a chunk element representing the updated chunk from at least one chunk element to which the original removal period is mapped;

determining, from the removal period list, a target updated removal period in which the updated expiration time falls; and

mapping a chunk element representing the updated chunk to the target updated removal period.