Method and system for managing weakly mutable data in a distributed storage system

1. A computer-implemented method for managing multiple generations of an object within a distributed storage system, wherein the distributed storage system includes a plurality of storage sub-systems having one or more processors and memory storing one or more programs for execution by the one or more processors to perform the method, comprising:

receiving metadata and content of a first generation of an object from a first client connected to the distributed storage system, wherein the first generation is identified by an object ID and a first generation ID;

storing the first generation's metadata and content within a first storage sub-system of the distributed storage system;

receiving metadata and content of a second generation of the object from a second client connected to the distributed storage system, wherein the second generation is identified by the object ID and a second generation ID;

storing the second generation's metadata and content within a second storage sub-system of the distributed storage system; and

independently replicating the first generation's metadata and content from the first storage sub-system to the second storage sub-system and replicating the second generation's metadata and content from the second storage sub-system to the first storage sub-system such that both the first and second storage sub-systems include a replica of the object's first and second generations, wherein each generation ID includes a first component that corresponds to a respective object generation's creation time and a second component that corresponds to a tie-breaker that defines an order among multiple generations of the same object and wherein the second generation's content is dynamically replicated from the second storage sub-system to the first storage sub-system in response to a first client request.

2. The computer-implemented method of claim 1 , wherein the content of either the first generation or the second generation is immutable over time until the deletion of the respective generation.

3. The computer-implemented method of claim 1 , wherein there is at least one content difference between the first generation and the second generation.

4. The computer-implemented method of claim 1 , further comprising:

at either of the first and second storage sub-systems,

comparing the first generation's content with the second generation's content; and

deleting one of the first generation and the second generation from a respective storage sub-system if the two generations have identical content.

5. The computer-implemented method of claim 1 , further comprising:

before the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system,

receiving a second client request for a latest generation of the object;

returning the first generation's content and metadata to the requesting client in response to the second client request;

after the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system,

receiving from a third client request for a latest generation of the object; and

returning the second generation's content and metadata to the requesting client in response to the third client request.

6. The computer-implemented method of claim 1 , further comprising:

at either of the first and second storage sub-systems,

determining a total number of generations of the object at the respective storage sub-system; and

deleting one or more generations of the object from the respective storage sub-system in accordance with their respective generation IDs if the total number of generations exceeds a predefined number associated with the object.

7. A computer system in association with a distributed storage system that includes a plurality of storage sub-systems, comprising:

one or more processors;

memory; and

one or more programs stored in the memory for execution by the one or more processors, the one or more programs comprising instructions for:

receiving metadata and content of a first generation of an object from a first client connected to the distributed storage system, wherein the first generation is identified by an object ID and a first generation ID;

storing the first generation's metadata and content within a first storage sub-system of the distributed storage system;

receiving metadata and content of a second generation of the object from a second client connected to the distributed storage system, wherein the second generation is identified by the object ID and a second generation ID;

storing the second generation's metadata and content within a second storage sub-system of the distributed storage system; and

independently replicating the first generation's metadata and content from the first storage sub-system to the second storage sub-system and replicating the second generation's metadata and content from the second storage sub-system to the first storage sub-system such that both the first and second storage sub-systems include a replica of the object's first and second generations, wherein each generation ID includes a first component that corresponds to a respective object generation's creation time and a second component that corresponds to a tie-breaker that defines an order among multiple generations of the same object and wherein the second generation's content is dynamically replicated from the second storage sub-system to the first storage sub-system in response to a first client request.

8. The computer system of claim 7 , wherein the content of either the first generation or the second generation is immutable over time until the deletion of the respective generation.

9. The computer system of claim 7 , wherein there is at least one content difference between the first generation and the second generation.

10. The computer system of claim 7 , further comprising:

at either of the first and second storage sub-systems,

instructions for comparing the first generation's content with the second generation's content; and

instructions for deleting one of the first generation and the second generation from a respective storage sub-system if the two generations have identical content.

11. The computer system of claim 7 , further comprising:

at the first storage sub-system,

instructions for receiving a second client request for a latest generation of the object before the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system;

instructions for returning the first generation's content and metadata to the requesting client in response to the second client request;

instructions for receiving from a third client request for a latest generation of the object after the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system; and

instructions for returning the second generation's content and metadata to the requesting client in response to the third client request.

12. The computer system of claim 7 , further comprising:

at either of the first and second storage sub-systems,

instructions for determining a total number of generations of the object at the respective storage sub-system; and

instructions for deleting one or more generations of the object from the respective storage sub-system in accordance with their respective generation IDs if the total number of generations exceeds a predefined number associated with the object.

13. A non-transitory computer readable storage medium storing one or more programs configured for execution by a server computer system having one or more processors and memory storing one or more programs for execution by the one or more processors in association with a distributed storage system that includes a plurality of storage sub-systems, the one or more programs comprising instructions to:

receive metadata and content of a first generation of an object from a first client connected to the distributed storage system, wherein the first generation is identified by an object ID and a first generation ID;

store the first generation's metadata and content within a first storage sub-system of the distributed storage system;

receive metadata and content of a second generation of the object from a second client connected to the distributed storage system, wherein the second generation is identified by the object ID and a second generation ID;

store the second generation's metadata and content within a second storage sub-system of the distributed storage system; and

independently replicate the first generation's metadata and content from the first storage sub-system to the second storage sub-system and replicate the second generation's metadata and content from the second storage sub-system to the first storage sub-system such that both the first and second storage sub-systems include a replica of the object's first and second generations, wherein each generation ID includes a first component that corresponds to a respective object generation's creation time and a second component that corresponds to a tie-breaker that defines an order among multiple generations of the same object and wherein the second generation's content is dynamically replicated from the second storage sub-system to the first storage sub-system in response to a first client request.

14. The non-transitory computer readable storage medium of claim 13 , wherein the content of either the first generation or the second generation is immutable over time until the deletion of the respective generation.

15. The non-transitory computer readable storage medium of claim 13 , wherein there is at least one content difference between the first generation and the second generation.

16. The non-transitory computer readable storage medium of claim 13 , further comprising:

at either of the first and second storage sub-systems,

instructions for comparing the first generation's content with the second generation's content; and

instructions for deleting one of the first generation and the second generation from a respective storage sub-system if the two generations have identical content.

17. The non-transitory computer readable storage medium of claim 13 , further comprising:

at the first storage sub-system,

instructions for receiving a second client request for a latest generation of the object before the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system;

instructions for returning the first generation's content and metadata to the requesting client in response to the second client request;

instructions for receiving from a third client request for a latest generation of the object after the replication of the second generation's metadata from the second storage sub-system to the first storage sub-system; and

instructions for returning the second generation's content and metadata to the requesting client in response to the third client request.

18. The non-transitory computer readable storage medium of claim 13 , further comprising:

at either of the first and second storage sub-systems,

instructions for determining a total number of generations of the object at the respective storage sub-system; and

instructions for deleting one or more generations of the object from the respective storage sub-system in accordance with their respective generation IDs if the total number of generations exceeds a predefined number associated with the object.