Apparatus and method for managing data storage

• US 8,326,897 B2
• Filed: 12/18/2008
• Issued: 12/04/2012
• 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:
  US12/338,931
• Publication Number:
  US 20090177857A1
• Time in Patent Office: 1,447 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 data storage area storing data in a storage device, wherein the first log structured data storage area includes a first portion of a segment data area in the storage device to store user data;

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

a second log structured storage area in the storage device storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area for storing the metadata is nested within the first log structured data storage area, and wherein the second log structured data storage area includes a track data area and a second portion of the segment data area to provide a virtual track data area in which the second log structured storage system allocates the physical storage to store the metadata for the data; and

a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area.

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

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 storage area.

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. The system of claim 1, wherein the storage device further includes a first portion of a superblock area used by the first log structured data storage system and a second portion of the superblock area used by the second log structured data storage system to provide the virtual track data area.

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

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

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

a second log structured storage area in the storage device storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area for storing the metadata is nested within the first log structured data storage area;

a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area;

a divider sub-component to divide each log structured data storage area for storing metadata into a working half and a backup half;

a first copier sub-component to copy the metadata from the working half to the backup half of each log structured data storage area for storing metadata;

a determiner sub-component to determine for a record in the backup half of each log structured data storage area for storing metadata whether corresponding data in a log structured data area is to be copied; and

a second copier sub-component to copy the data in the log structured data area in response to determining that the data in the log structured data area is to be copied.

11. A method, comprising:

providing a first log structured data storage area storing data in a storage device, wherein the first log structured data storage area includes a first portion of a segment data area in the storage device to store user data;

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

providing a second log structured storage area in the storage device storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area storing the metadata for the first log structured data storage system is nested within the first log structured data storage area, wherein the second log structured data storage area includes a track data area and a second portion of the segment data area to provide a virtual track data area in which the second log structured storage system allocates the physical storage to store the metadata for the data; and

providing a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area.

12. The method of claim 11, further comprising providing a third log structured data storage area for storing further metadata of the second log structured data storage system, wherein the third log structured data storage area is nested within the second log structured data storage area.

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

14. The method of claim 13, wherein the unused metadata comprises an all-zeroes pattern or wherein the unused metadata comprises an all-ones pattern.

15. The method of claim 11, further comprising compressing the metadata before writing.

16. The method of claim 11, further comprising taking a snapshot copy of the metadata in the second storage area.

17. The method of claim 11, 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.

18. The method of claim 17, further comprising performing write caching, and wherein the data deduplication is performed during a cache destage.

19. The computer readable storage medium of claim 11, further comprising taking a snapshot copy of the metadata in the second storage area.

20. The method of claim 11, wherein the storage device further includes a first portion of a superblock area used by the first log structured data storage system and a second portion of the superblock area used by the second log structured data storage system to provide the virtual track data area.

21. A method, comprising:

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

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

providing a second log structured storage area in the storage device storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area storing the metadata for the first log structured data storage system is nested within the first log structured data storage area;

providing a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area;

dividing each log structured data storage area for storing metadata into a working half and a backup half;

copying the metadata from the working half to the backup half of each log structured data storage area for storing metadata;

determining for a record in the backup half of each log structured data storage area for storing metadata whether corresponding data in a log structured data area is to be copied; and

copy the data in the log structured data area in response to determining that the data in the log structured data area is to be copied.

22. tangible computer readable storage device 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 data storage area storing data in the storage device, wherein the first log structured data storage area includes a first portion of a segment data area in the storage device to store user data;

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

providing a second log structured data storage area storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area storing the metadata for the first log structured data storage system is nested within the first log structured data storage area, wherein the second log structured data storage area includes a track data area and a second portion of the segment data area to provide a virtual track data area in which the second log structured storage system allocates the physical storage to store the metadata for the data; and

Providing a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area.

23. The computer storage readable medium of claim 22, wherein the operations further comprise:

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

24. The computer readable storage medium of claim 22, wherein unused metadata is recognizable patterned data.

25. The computer readable storage medium of claim 22, wherein the operations further comprise compressing the metadata before writing.

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

27. The computer storage readable medium of claim 22, wherein the storage device further includes a first portion of a superblock area used by the first log structured data storage system and a second portion of the superblock area used by the second log structured data storage system to provide the virtual track data area.

28. A tangible computer readable storage device 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 data storage area storing data in the storage device;

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

providing a second log structured data storage area storing metadata for the data in the first log structured data storage area, wherein the second log structured data storage area storing the metadata for the first log structured data storage system is nested within the first log structured data storage area;

providing a second log structured storage system operable with the second log structured storage area, wherein the second log structured storage system allocates address space in the second log structured storage area for the metadata on demand when the first log structured storage system requires the allocation of address space for metadata for data the first log structured storage system stored in the first log structured storage area;

dividing each log structured data storage area for storing metadata into a working half and a backup half;

copying the metadata from the working half to the backup half of each log structured data storage area for storing metadata;

determining for a record in the backup half of each log structured data storage area for storing metadata whether corresponding data in a log structured data area is to be copied; and

copy the data in the log structured data area in response to determining that the data in the log structured data area is to be copied.