Data storage using identifiers

• US 7,599,932 B2
• Filed: 10/20/2006
• Issued: 10/06/2009
• Est. Priority Date: 06/30/2003
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Data Domain, Inc. (Dell Technologies Inc.)
• Inventors: Patterson, R. Hugo
• Primary Examiner(s): Sough; Hyung S
• Assistant Examiner(s): PATEL, KAUSHIKKUMAR M
• Application Number:
  US11/584,433
• Publication Number:
  US 20070101074A1
• Time in Patent Office: 1,082 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1744 using compression, e.g. sparse files
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A system and method are disclosed for processing a data stream. A data segment is received. It is determined whether the data segment has been previously stored. In the event that the data segment is determined not to have been previously stored, a unique identifier for specifying the data segment in a representation of the data stream is generated.

Claims

1. A method for processing a data stream comprising:

receiving a data segment;

determining whether the data segment has been previously stored; and

in the event that the data segment is determined not to have been previously stored, generating a unique identifier for uniquely specifying the data segment in a representation of the data stream without probability of collision with a different data segment in the data stream;

wherein

generating the unique identifier includes;

deriving a content derived summary based on content of the data segment;

determining whether a portion of the content derived summary has been previously stored; and

in the event that the portion of the content derived summary has not been previously stored, using the portion of the content derived summary as a unique identifier;

and wherein

the unique identifier is different from the content derived summary.

2. A method as recited in claim 1, wherein no unique identifier for specifying the data segment in a representation of the data stream is generated in the event that the data segment is determined to have been previously stored.

3. A method as recited in claim 1, wherein determining whether the data segment has been previously stored does not require using the unique identifier.

4. A method as recited in claim 1, further comprising, in the event that the data segment is determined to have been previously stored, reusing a previously generated unique identifier associated with the data segment.

5. A method as recited in claim 1, further comprising, in the event that the data segment is determined to have been previously stored, looking up a previously generated unique identifier associated with the data segment.

6. A method as recited in claim 1, further comprising, in the event that the data segment is determined not to have been previously stored:

storing the data segment in a data segment storage location; and

recording the data segment storage location.

7. A method as recited in claim 6, wherein the data segment storage location includes a memory address.

8. A method as recited in claim 1, in the event that the data segment is determined not to have been previously stored, further including:

storing the data segment in a data segment storage location; and

updating a data structure for storing the content derived summary, the unique identifier, and the data segment storage location.

9. A method as recited in claim 1 in the event that the data segment is determined not to have been previously stored, further including:

storing the data segment in a data segment storage location; and

updating a data structure for storing the content derived summary, the unique identifier, and the data segment storage location;

wherein

the data segment storage location is accessed given the unique identifier or given the content derived summary in the data structure.

10. A method as recited in claim 1,

in the event that the data segment is determined not to have been previously stored, further including:

storing the data segment in a data segment storage location; and

updating a data structure for storing the content derived summary, the unique identifier, and the data segment storage location;

wherein

the data segment storage location is accessed given the unique identifier or given the content derived summary, using a single access of a storage device.

11. A method for processing a data stream as recited in claim 1,

in the event that the data segment is determined not to have been previously stored, further including:

storing the data segment in a data segment storage location; and

updating a data structure for storing the content derived summary, the unique identifier, and the data segment storage location;

wherein

a region of the data structure that includes the data segment storage location is accessed given the unique identifier or given the content derived summary, using a single access of a storage device.

12. A method for processing a data stream as recited in claim 1, wherein determining whether the data segment has been previously stored includes generating a content derived summary for the data segment;

and the unique identifier is derived from the content derived summary.

13. A method as recited in claim 1, in the event that the portion of the content derived summary has been previously stored, modifying a value that corresponds to the portion of the content derived summary to derive the unique identifier.

14. A system for processing data stream comprising:

an interface configured to receive a data segment;

a processor coupled to the interface, configured to;

determine whether the data segment has been previously stored; and

in the event that the data segment is determined not to have been previously stored, generate a unique identifier for uniquely specifying the data segment in a representation of the data stream without probability of collision with a different data segment in the data stream;

wherein

generating the unique identifier includes;

deriving a content derived summary based on content of the data segment;

determining whether a portion of the content derived summary has been previously stored;

in the event that the portion of the content derived summary has not been previously stored, using the portion of the content derived summary as a unique identifier;

wherein

the unique identifier is different from the content derived summary.

15. A system as recited in claim 14, wherein no unique identifier for specifying the data segment in a representation of the data stream is generated in the event that the data segment is determined to have been previously stored.

16. A system as recited in claim 14, wherein determining whether the data segment has been previously stored does not require using the unique identifier.

17. A system as recited in claim 14, the processor is further configured, in the event that the portion of the content derived summary has been previously stored, to modify a value that corresponds to the portion of the content derived summary to derive the unique identifier.

18. A computer program product for processing a data stream, the computer program product being embodied in a computer readable storage medium and comprising computer instructions for:

receiving a data segment;

determining whether the data segment has been previously stored; and

in the event that the data segment is determined not to have been previously stored, generating a unique identifier uniquely specifying the data segment in a representation of the data stream without probability of collision with a different data segment in the data stream;

wherein

generating the unique identifier includes;

deriving a content derived summary based on content of the data segment;

determining whether a portion of the content derived summary has been previously stored; and

in the event that the portion of the content derived summary has not been previously stored, using the portion of the content derived summary as a unique identifier;

and wherein

the unique identifier is different from the content derived summary.

19. A computer program product as recited in claim 18, wherein no unique identifier for specifying the data segment in a representation of the data stream is generated in the event that the data segment is determined to have been previously stored.

20. A computer program product as recited in claim 18, wherein determining whether the data segment has been previously stored does not require using the unique identifier.

21. A computer program product as recited in claim 18, further comprising computer instructions for in the event that the portion of the content derived summary has been previously stored, modifying a value that corresponds to the portion of the content derived summary to derive the unique identifier.