Space recovery with storage management coupled with a deduplicating storage system

• US 7,984,022 B2
• Filed: 04/18/2008
• Issued: 07/19/2011
• Est. Priority Date: 04/18/2008
• Status: Active Grant

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Smith, Mark Andrew, Cannon, David Maxwell
• Primary Examiner(s): Lu; Kuen S
• Assistant Examiner(s): LIAO, JASON G
• Application Number:
  US12/105,892
• Publication Number:
  US 20090265399A1
• Time in Patent Office: 1,187 Days
• Field of Search: None
• US Class Current: 707/664
• CPC Class Codes: G06F 16/1727 Details of free space management performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064
• 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

Abstract

Provided are techniques for space recovery with storage management coupled with a deduplicating storage system. A notification is received that one or more data objects have been logically deleted by deleting metadata about the one or more data objects, wherein the notification provides storage locations within one or more logical storage volumes corresponding to the deleted one or more data objects, wherein each of the one or more data objects are divided into one or more extents. In response to determining that a sparse file represents the one or more logical storage volumes, physical space is deallocated by nulling out space in the sparse file corresponding to each of the one or more extents.

Claims

1. A computer-implemented method, comprising:

under control of a storage-management server,

storing metadata about data objects in a database;

in response to a request to delete one or more data objects stored in data storage, logically deleting the one or more data objects by deleting the metadata about the one or more data objects in the database; and

sending a notification that the one or more data objects have been logically deleted by deleting the metadata about the one or more data objects, wherein the notification provides storage locations within one or more logical storage volumes corresponding to the deleted one or more data objects, wherein each of the one or more data objects are divided into one or more extents; and

under control of a deduplicating storage system that is separate from and coupled to the storage-management server,

receiving the notification; and

in response to determining that a sparse file represents the one or more logical storage volumes, recovering the physical space occupied by unused extents without moving data and without forcing updates to storage location information tracked by the storage-management server by nulling out space in the sparse file corresponding to each of the one or more extents.

2. The computer-implemented method of claim 1, at the storage-management server, further comprising:

tracking the one or more data objects by storing the metadata about the data objects;

receiving a request to delete the one or more data objects;

logically deleting the one or more data objects by deleting the metadata about the one or more data objects; and

in response to logically deleting the one or more data objects, sending the notification of one or more storage locations occupied by the one or more data objects, wherein each storage location provides an offset into a logical storage volume and a length of a data object.

3. The computer-implemented method of claim 1, at the deduplicating storage system, further comprising:

dereferencing the one or more extents corresponding to the storage locations by maintaining a reference count of a number of references to each extent and decrementing the reference count for each extent corresponding to a deleted extent, wherein an extent is eligible for space reclamation when the references to the extent have been removed.

4. The computer-implemented method of claim 1, at the deduplicating storage system, further comprising:

in response to determining that there is one file for each extent, recovering physical space by deleting the file corresponding to the extent.

5. The computer-implemented method of claim 1, at the deduplicating storage system, further comprising:

in response to determining that the notification specifies offsets for storage locations that do not align with extent boundaries, performing one of truncating the one or more extents to fit within the extent boundaries and copying-on-write.

6. The computer-implemented method of claim 1, at the deduplicating storage system, further comprising:

removing extent metadata for the one or more extents.

7. The method of claim 1, at the deduplicating storage system, further comprising:

determining that it is time to perform storage space reclamation based on one or more storage policies.

8. A computer program product, comprising a:

a first computer-readable medium storing a first computer readable program, wherein the first computer-readable medium is a member of a set of computer readable media consisting of a semiconductor or solid state memory, a magnetic tape, a removable computer diskette, a rigid magnetic disk, an optical disk, a magnetic storage medium, and volatile and non-volatile memory devices, and wherein the first computer readable program, when executed, causes a storage-management server to;

store metadata about data objects in a database;

in response to a request to delete one or more data objects stored in data storage, logically delete the one or more data objects by deleting the metadata about the one or more data objects in the database; and

send a notification that the one or more data objects have been logically deleted by deleting the metadata about the one or more data objects, wherein the notification provides storage locations within one or more logical storage volumes corresponding to the deleted one or more data objects, wherein each of the one or more data objects are divided into one or more extents; and

a second computer-readable medium storing a second computer readable program, wherein the second computer readable program, when executed, causes a deduplicating storage system, that is separate from and coupled to the storage-management server, to;

receive the notification; and

in response to determining that a sparse file represents the one or more logical storage volumes, recover the physical space occupied by unused extents without moving data and without forcing updates to storage location information tracked by the storage-management server by nulling out space in the sparse file corresponding to each of the one or more extents.

9. The computer program product of claim 8, wherein the first computer readable program when executed causes the storage-management server to:

track the one or more data objects by storing the metadata about the data objects;

receive a request to delete the one or more data objects;

logically delete the one or more data objects by deleting the metadata about the one or more data objects; and

in response to logically deleting the one or more data objects, send the notification of one or more storage locations occupied by the one or more data objects, wherein each storage location provides an offset into a logical storage volume and a length of a data object.

10. The computer program product of claim 8, wherein the second computer readable program when executed causes the deduplicating storage system to:

dereference the one or more extents corresponding to the storage locations by maintaining a reference count of a number of references to each extent and decrementing the reference count for each extent corresponding to a deleted extent, wherein an extent is eligible for space reclamation when the references to the extent have been removed.

11. The computer program product of claim 8, wherein the second computer readable program when executed causes the deduplicating storage system to:

in response to determining that there is one file for each extent, recover physical space by deleting the file corresponding to the extent.

12. The computer program product of claim 8, wherein the second computer readable program when executed causes the deduplicating storage system to:

in response to determining that the notification specifies offsets for storage locations that do not align with extent boundaries, perform one of truncating the one or more extents to fit within the extent boundaries and copying-on-write.

13. The computer program product of claim 8, wherein the second computer readable program when executed causes the deduplicating storage system to:

remove extent metadata for the one or more extents.

14. A system, comprising:

hardware logic at a storage-management server performing operations, the operations comprising;

storing metadata about data objects in a database;

in response to a request to delete one or more data objects stored in data storage, logically deleting the one or more data objects by deleting the metadata about the one or more data objects in the database; and

sending a notification that the one or more data objects have been logically deleted by deleting the metadata about the one or more data objects, wherein the notification provides storage locations within one or more logical storage volumes corresponding to the deleted one or more data objects, wherein each of the one or more data objects are divided into one or more extents; and

hardware logic at a deduplicating storage system, that is separate from and coupled to the storage-management server, performing operations, the operations comprising;

receiving the notification; and

in response to determining that a sparse file represents the one or more logical storage volumes, recovering the physical space occupied by unused extents without moving data and without forcing updates to storage location information tracked by the storage-management server by nulling out space in the sparse file corresponding to each of the one or more extents.

15. The system of claim 14, wherein the operations at the storage-management server further comprise:

tracking the one or more data objects by storing the metadata about the data objects;

receiving a request to delete the one or more data objects;

logically deleting the one or more data objects by deleting the metadata about the one or more data objects; and

in response to logically deleting the one or more data objects, sending the notification of one or more storage locations occupied by the one or more data objects, wherein each storage location provides an offset into a logical storage volume and a length of a data object.

16. The system of claim 14, wherein the operations at the deduplicating storage system further comprise:

dereferencing the one or more extents corresponding to the storage locations by maintaining a reference count of a number of references to each extent and decrementing the reference count for each extent corresponding to a deleted extent, wherein an extent is eligible for space reclamation when the references to the extent have been removed.

17. The system of claim 14, wherein the operations at the deduplicating storage system further comprise:

in response to determining that there is one file for each extent, recovering physical space by deleting the file corresponding to the extent.

18. The system of claim 14, wherein the operations at the deduplicating storage system further comprise:

in response to determining that the notification specifies offsets for storage locations that do not align with extent boundaries, performing one of truncating the one or more extents to fit within the extent boundaries and copying-on-write.

19. The system of claim 14, wherein the operations at the deduplicating storage system further comprise:

removing extent metadata for the one or more extents.