APPARATUS AND METHOD FOR MANAGING DATA STORAGE

• US 20180276075A1
• Filed: 05/25/2018
• Published: 09/27/2018
• Est. Priority Date: 12/19/2007
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Butterworth, Henry Esmond, Judd, Ian David
• Granted Patent: US 10,445,180 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1453 using de-duplication of the data
• CPC Class Codes: G06F 12/0808 with cache invalidating means G06F12/0815 takes precedence
• CPC Class Codes: G06F 16/1847 specifically adapted to static storage, e.g. adapted to flash memory or SSD
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 2212/62 Details of cache specific to multiprocessor cache arrangements

Abstract

Provided are an apparatus and method for managing data storage. A first log structured array stores data in a storage device. A second log structured array in the storage device stores metadata for the data in the first log structured array, wherein the second log structured array storing the metadata for the first log structured data storage system is nested within the first log structured array, and wherein the first and second log structured arrays comprise separate instances of log structured arrays. Address space is allocated in the second log structured array for metadata when the allocation of address space is required for metadata for data stored in the first log structured array.

Claims

1. A system in communication with data storage, for storing data, and comprising:

a first log structured array storing data in a storage device;

a second log structured array in the storage device storing metadata for the data in the first log structured array, wherein the second log structured array is nested within the first log structured array, and wherein the first and second log structured arrays comprise separate instances of log structured arrays; and

a component for allocating address space in the second log structured array for metadata when the allocation of address space is required for metadata for data stored in the first log structured array.

2. The system of claim 1, further comprising a third log structured array for storing further metadata, wherein the third log structured array is nested within the second log structured array.

3. The system of claim 1, further comprising a compression component for compressing the metadata before writing.

4. The system of claim 1, further comprising a snapshot component for taking a snapshot copy of the metadata in the second log structured array.

5. The system of claim 1, further comprising a data deduplication component comprising:

a hashing component for creating and storing a hash value of a data entity;

a comparator for comparing hash values of a pair of data entities; and

a write control component responsive to an output of said comparator for selectively writing a non-duplicate data entity and for creating a snapshot of a duplicate data entity.

6. The system of claim 5, further comprising a write cache component, and wherein said data deduplication component is operable during a cache destage.

18. The system of claim 1, further comprising:

a metadata area in the storage device including a second log structured array metadata area, wherein the component allocates part of the second log structured array metadata area for metadata for the first log structured array.

7. A method, comprising:

providing a first log structured array storing data in a storage device;

providing a second log structured array in the storage device storing metadata for the data in the first log structured array, wherein the second log structured array storing the metadata for the first log structured data storage system is nested within the first log structured array, and wherein the first and second log structured arrays comprise separate instances of log structured arrays; and

allocating address space in the second log structured array for metadata when the allocation of address space is required for metadata for data stored in the first log structured array.

8. The method of claim 7, further comprising:

providing a third log structured array for storing further metadata, wherein the third log structured array is nested within the second log structured array.

9. The method of claim 7, further comprising:

compressing the metadata before writing.

10. The method of claim 7, further comprising:

taking a snapshot copy of the metadata in the second log structured array.

11. The method of claim 7, further comprising performing data deduplication by performing:

creating and storing a hash value of a data entity;

comparing hash values of a pair of data entities to determine whether the data entity is a duplicate; and

responsive to an output of comparing the hash values, selectively writing a non-duplicate data entity and creating a snapshot of a duplicate data entity.

12. The method of claim 11, further comprising performing write caching, and wherein the data deduplication is performed during a cache destage.

19. The method of claim 7, further comprising:

providing a metadata area in the storage device including a second log structured array metadata area, wherein the component allocates part of the second log structured array metadata area for metadata for the first log structured array.

13. A computer readable storage medium including a computer program, that when loaded into a computer system and executed thereon, causes the computer system to communicate with a storage device and to perform operations, the operations comprising:

providing a first log structured array storing data in the storage device;

providing a second log structured array in the storage device storing metadata for the data in the first log structured array, wherein the second log structured array is nested within the first log structured array, and wherein the first and second log structured arrays comprise separate instances of log structured arrays; and

allocating address space in the second log structured array for metadata when the allocation of address space is required for metadata for data stored in the first log structured array.

14. The computer storage readable medium of claim 13, wherein the operations further comprise:

providing a third log structured array for storing further metadata, wherein the third log structured array is nested within the second log structured array.

15. The computer readable storage medium of claim 13, wherein the operations further comprise:

taking a snapshot copy of the metadata in the second log structured array.

16. The computer storage readable medium of claim 13, further comprising performing data deduplication by performing:

creating and storing a hash value of a data entity;

comparing hash values of a pair of data entities to determine whether the data entity is a duplicate; and

responsive to an output of comparing the hash values, selectively writing a non-duplicate data entity and creating a snapshot of a duplicate data entity.

17. The computer storage readable medium of claim 16, wherein the operations further comprise:

performing write caching, and wherein the data deduplication is performed during a cache destage.

20. The computer storage readable medium of claim 13, wherein the operations further comprise:

providing a metadata area in the storage device including a second log structured array metadata area, wherein the component allocates part of the second log structured array metadata area for metadata for the first log structured array.