Offload Read and Write Offload Provider

• US 20130179649A1
• Filed: 01/09/2012
• Published: 07/11/2013
• Est. Priority Date: 01/09/2012
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Green, Dustin L., Nagar, Rajeev, Christiansen, Neal R.
• Granted Patent: US 9,817,582 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0673 Single storage device

Abstract

Aspects of the subject matter described herein relate to an offload provider. In aspects, an offload provider may provide a token that represents data. The offload provider may be expected to ensure that the data the token represents will not change while the token is valid. The offload provider may take actions to ensure the immutability of the data. The actions may be taken, for example, in conjunction with receiving an offload read and/or offload write, and/or in conjunction with receiving another write that, if allowed to proceed, would otherwise change the data represented by the token.

Claims

1. A method implemented at least in part by a computer, the method comprising:

at a data access component, receiving a write request directed at a storage container, the write request involving storage locations of data represented by a token, the token previously issued by an offload provider responsible for ensuring that the data represented by the token is not allowed to change while the token is valid;

in response to receiving the write request, performing an action, the action depending on implementation of the offload provider, the action including one or more of;

invalidating the token,

copying the data affected by the write request to another storage location,

copying the data affected by the write request to other memory that includes volatile and/or nonvolatile elements in conjunction with updating the token to reference the other memory,

unsparing shared storage locations used to store the data, and

causing the write request to write to a new storage location that does not affect the data represented by the token.

2. The method of claim 1, further comprising not allowing the write request to proceed to another data access component until in-progress offload writes, if any, involving the token are completed.

3. The method of claim 2, further comprising cancelling or truncating one or more of the in-progress offload writes.

4. The method of claim 1, further comprising placing a reference to a range of the data in a destination write cache prior to receiving the write request and after receiving the write request, copying the range of the data into the write cache or a destination storage container prior to allowing the write request to modify data in the range.

5. The method of claim 1, further comprising:

prior to receiving the write request, updating a sharing data structure that tracks physical data used to share data between two or more storage containers, creating the token, and causing the token to reference a portion of the physical data, the updating the sharing data structure causing the sharing data structure to share the portion of the physical data for representation by the token;

after receiving the write request, updating the sharing data structure to unshare the physical data for the destination of the write request; and

allowing the write request to proceed.

6. The method of claim 5, further comprising updating a reverse-map data structure in conjunction with updating the sharing data structure, the reverse-map data structure tracking usage of physical data by a logical storage container.

7. The method of claim 1, further comprising performing a garbage collection of storage to maintain data structures that use physical data to back two or more logical copies.

8. The method of claim 1, further comprising:

receiving an offload read request prior to receiving the write request; and

in response to receiving the offload read request, obtaining an opportunistic lock on the data.

9. The method of claim 1, further comprising:

after receiving an offload write request in conjunction with the token, updating a sharing data structure that tracks physical data used to share data between two or more storage containers, and causing a destination of the offload write to reference a portion of the physical data, the portion of the physical data also associated with the token, the updating the sharing data structure causing the sharing data structure to share the portion of the physical data between the destination of the offload write and the token;

after receiving the write request, updating the sharing data structure to unshare the portion of the physical data for a destination of the write request, and allowing the write request to proceed.

10. The method of claim 9, wherein performing the action comprises performing the action prior to releasing the opportunistic lock on the data.

11. The method of claim 1, further comprising:

receiving an offload read request prior to receiving the write request; and

in response to receiving the offload read request, copying data associated with the token to memory prior to providing the token.

12. The method of claim 11, further comprising copying the data associated with the token to additional memory prior to receiving the write request, the additional memory including one or more of volatile and nonvolatile memory.

13. The method of claim 1, further comprising receiving an offload read request prior to receiving the write request, and in response creating a token that is associated with data of the storage container, the storage container being a read-only storage container when the offload read request is received.

14. The method of claim 13, further comprising creating a snapshot of the read-only storage container prior to allowing the write request to change the storage container to a read-write storage container, the write request being a request to change the storage container to a read-write storage container.

15. The method of claim 14, wherein creating a snapshot of the read-only storage container comprises creating a snapshot for the entire read-only storage container.

16. The method of claim 14, wherein creating a snapshot of the read-only storage container comprises creating a snapshot of a portion of the read-only storage container, the portion backing the data of the token.

17. In a computing environment, a system, comprising:

an offload provider operable to provide a token in response to receiving an offload read request, the token initially representing data of a storage container, the offload provider responsible for ensuring that the data represented by the token is not allowed to change while the token is valid, the offload provider further operable to receive a write request and determine that the write request involves storage locations also used to store data represented by the token, the offload provider further operable to take action to ensure that the data represented by the token is not allowed to change while the token is valid, the action including one or more of;

invalidating the token,

copying the data to another location in response to receiving the write request,

unsparing shared storage used to store the data,

logically copying the data to another location in conjunction with providing the token in response to receiving the offload read request,

in performing a logical write, writing a portion of the logically-written data to a newly-allocated physical storage location,

taking a snapshot of the storage container or a portion thereof, and

associating the token with a portion of a read-only storage container that logically includes the data.

18. The system of claim 17, wherein the offload provider is operable to ensure that the token is not allowed to change by being operable to take an additional action, the additional action including obtaining an opportunistic lock on the data in conjunction with providing the token in response to receiving the offload read request.

19. The system of claim 17, further comprising a storage system operable to use a data structure to cause physical data to back two or more logical containers, the offload provider further operable to cause the storage system to use the data structure to back the data represented by the token.

20. A method implemented at least in part by a computer, the method comprising:

sending an offload read request to an offload provider, the offload provider operable to provide a token in response to receiving the offload read request, the token representing data of a storage container, the offload provider responsible for ensuring that the data represented by the token is not allowed to change while the token is valid;

receiving the token;

sending a write request that involves the data represented by the token, the offload provider further operable to take action to ensure that the data represented by the token is not allowed to change while the token is valid, the action including one or more of;

invalidating the token,

copying the data to another location in response to receiving the write request,

unsparing shared storage used to store the data,

logically copying the data to another location in conjunction with providing the token in response to receiving the offload read request,

in servicing a write request, writing a portion of the data as indicated by the write request to a newly-allocated physical storage location,

taking a snapshot of the storage container or a portion thereof, and

associating the token with a read-only storage container that logically includes the data.