Apparatus and method for managing data storage

• US 8,914,425 B2
• Filed: 08/07/2012
• Issued: 12/16/2014
• Est. Priority Date: 12/19/2007
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Butterworth, Henry Esmond, Judd, Ian David
• Primary Examiner(s): Chbouki, Tarek
• Application Number:
  US13/569,067
• Publication Number:
  US 20120303902A1
• Time in Patent Office: 861 Days
• Field of Search: None
• US Class Current: 707/822
• 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

An apparatus for controlling a log-structured data storage system, operable with a first log-structured data storage area for storing data, comprises a metadata storage component for controlling the first log-structured data storage area and comprising a second log-structured data storage area for storing metadata; and means for nesting the second log-structured data storage area for storing metadata within the first log-structured data storage area. The apparatus may further comprise at least a third log-structured data storage area for storing further metadata, and means for nesting the at least a third log-structured data storage area within the second log-structured data storage area.

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 first log structured data storage system operable with the first log structured array to store the data in the first log structured array;

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

a second log structured storage system operable with the second log structured array, wherein the second log structured storage system allocates address space in the second log structured array for the metadata when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stores in the first log structured array; and

a superblock area storing data for both the first and second log structured arrays, wherein the second log structured array uses a portion of the superblock area to provide a data area in which the first log structured array stores metadata.

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

3. The system of claim 1, wherein unused metadata is recognizable patterned data.

4. The system of claim 3, wherein the unused metadata comprises an all-zeroes pattern or wherein the unused metadata comprises an all-ones pattern.

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

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

7. 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.

8. The system of claim 7, further comprising a write cache component, and wherein said data deduplication component is operable during a cache destage.

9. A method, comprising:

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

providing a first log structured data storage system operable with the first log structured array to store the data in the first log structured array;

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;

providing a second log structured storage system operable with the second log structured array, wherein the second log structured storage system allocates address space in the second log structured array for the metadata when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stores in the first log structured array; and

a superblock area storing data for both the first and second log structured arrays, wherein the second log structured array uses a portion of the superblock area to provide a data area in which the first log structured array stores metadata.

10. The method of claim 9, further comprising providing a third log structured array for storing further metadata of the second log structured data storage system, wherein the third log structured array is nested within the second log structured array.

11. The method of claim 9, wherein unused metadata is recognizable patterned data.

12. The method of claim 11, wherein the unused metadata comprises an all-zeroes pattern or wherein the unused metadata comprises an all-ones pattern.

13. The method of claim 9, further comprising compressing the metadata before writing.

14. The method of claim 9, further comprising taking a snapshot copy of the metadata in the second log structured array.

15. The method of claim 9, 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.

16. The method of claim 15, further comprising performing write caching, and wherein the data deduplication is performed during a cache destage.

17. 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 first log structured data storage system operable with the first log structured array to store the data in the first log structured array;

providing a second log structured array 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;

providing a second log structured storage system operable with the second log structured array, wherein the second log structured storage system allocates address space in the second log structured array for the metadata when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stores in the first log structured array; and

a superblock area storing data for both the first and second log structured arrays, wherein the second log structured array uses a portion of the superblock area to provide a data area in which the first log structured array stores metadata.

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

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

19. The computer readable storage medium of claim 17, wherein unused metadata is recognizable patterned data.

20. The computer readable storage medium of claim 17, wherein the operations further comprise compressing the metadata before writing.

21. The computer readable storage medium of claim 17, further comprising taking a snapshot copy of the metadata in the second log structured array.

22. The computer storage readable medium of claim 17, 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.