Apparatus and method for data replication at an intermediate node

• US 20060218210A1
• Filed: 03/25/2005
• Published: 09/28/2006
• Est. Priority Date: 03/25/2005
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Sarma, Joydeep, Federwisch, Michael, Watanabe, Steven, Rowe, Alan Lawson
• Granted Patent: US 7,631,021 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

An embodiment of the invention provides an apparatus that includes a primary node, a secondary node, and an intermediate node. Data is synchronously copied from the primary node to the intermediate node, and data is asynchronously copied from the intermediate node to the secondary node. The data stored in the intermediate node is a subset of the data set that is stored in the primary node. Therefore, an embodiment of the invention advantageously provides a multiple hop data replication method that allows data recovery if disaster occurs at the location of the primary node. Additionally, an embodiment of the invention advantageously provides a tolerable latency value from the time that a client device sends a write request to the primary node to the time that an acknowledgement message is received by the client device.

Claims

1. A method for data replication, the method comprising:

receiving data from a primary node;

storing the data in an intermediate node;

forwarding the data to a secondary node; and

storing the data in the secondary node, wherein the data is a subset of a data set stored in the primary node.

2. The method of claim 1, wherein the data set in the primary node is backed up in the secondary node.

3. The method of claim 1, further comprising:

sending the data to the primary node via a write request from a client device.

4. The method of claim 1, further comprising:

sending an acknowledgement message from the intermediate node to the primary node; and

forwarding the acknowledgement to a client device, wherein the acknowledgement message indicates that the intermediate node has stored the data.

5. The method of claim 1, wherein the data is synchronously copied from the primary node to the intermediate node.

6. The method of claim 1, wherein the data is asynchronously copied from the intermediate node to the secondary node.

7. The method of claim 1, wherein the primary node provides data storage services over a network.

8. The method of claim 1, wherein the secondary node provides data storage services over a network.

9. The method of claim 1, wherein the secondary node is located at a site that is remote from the primary node.

10. The method of claim 1, wherein the intermediate node is located between the primary node and secondary node.

11. The method of claim 1, further comprising:

providing direct communication between the primary node and the secondary node when the intermediate node is not available for communication in the network.

12. The method of claim 1, further comprising:

sending a confirmation message from the secondary node to the intermediate node, in order to indicate that the data has been stored in the secondary node.

13. The method of claim 12, further comprising:

in response to the confirmation message, deleting the data in the intermediate node.

14. The method of claim 1, further comprising:

receiving, by the intermediate node, a first update from the primary node and a second update from the primary node; and

receiving, by the secondary node, the second update if the secondary node had previously received the first update.

15. The method of claim 1, further comprising:

receiving, by the intermediate node, a first update in a particular buffer space in the intermediate node and a second update in the particular buffer space in the intermediate node; and

forwarding, by the intermediate node, the second update to the secondary node.

16. The method of claim 1, further comprising:

defining a time point from time t_A to time t_B;

batching all updates that are received by the intermediate node during the time point into an aggregated update; and

sending the aggregated update to the secondary node.

17. A method for tolerating network outages, the method comprising:

detecting an occurrence of a network outage;

if the network outage is due to a failure between the intermediate node and the secondary node, or due to a failure of the secondary node, then storing data that is received from the primary node to the intermediate node; and

if the network outage is due to a failure between the primary node and intermediate node, or due to a failure of the intermediate node, then directly transmitting the data from the primary node to the secondary node.

18. The method of claim 17, further comprising:

after the failure between the intermediate node and secondary node has been eliminated, or after the failure of the secondary node has been eliminated, then transmitting the stored data from the intermediate node to the secondary node.

19. The method of claim 18, further comprising:

storing, in the secondary node, the data that is received from the intermediate node.

20. The method of claim 17, further comprising:

storing, in the secondary node, the data transmitted from the primary node.

21. A method for data replication, the method comprising:

receiving data from a first primary node;

storing the data in a first buffer space in an intermediate node;

forwarding the data to a first secondary node;

receiving other data from a second primary node;

storing the other data in a second buffer space in the intermediate node; and

forwarding the other data to a second secondary node.

22. The method of claim 21, further comprising:

storing the data in the first secondary node.

23. The method of claim 21, further comprising:

storing the other data in the second secondary node.

24. The method of claim 21, wherein the data stored in the first buffer space is a subset of the data set that is stored in the first primary node.

25. The method of claim 21, wherein the other data stored in the second buffer space is a subset of the data set that is stored in the second primary node.

26. The method of claim 21, wherein the data is a copy of a data written to the first primary node.

27. The method of claim 21, wherein the other data is a copy of a data written to the second primary node.

28. An apparatus for data replication, the apparatus comprising:

means for receiving data from a primary node;

means for storing the data in an intermediate node;

means for forwarding the data to a secondary node; and

means for storing the data in the secondary node, wherein the data is a subset of a data set stored in the primary node.

29. An article of manufacture comprising:

a machine-readable medium having stored thereon instructions to;

receive data from a primary node;

forward the data to a secondary node, wherein the data is stored in the secondary node and wherein the data is a subset of a data set stored in the primary node.

30. An apparatus for data replication, the apparatus comprising:

a primary node;

a secondary node; and

an intermediate node configured to receive data from the primary node, to store the data, and to forward the data to the secondary node, wherein the secondary node stores the data, and wherein the data is a subset of a data set stored in the primary node.

31. The apparatus of claim 30, wherein the data set in the primary node is backed up in the secondary node.

32. The apparatus of claim 30, wherein the data is sent to the primary node via a write request from a client device.

33. The apparatus of claim 30, wherein the intermediate node is configured to send an acknowledgement message to the primary node, wherein the primary node is configured to forward the acknowledgement message to a client device, and wherein the acknowledgement message indicates that the intermediate node has stored the data.

34. The apparatus of claim 30, wherein the data is synchronously copied from the primary node to the intermediate node.

35. The apparatus of claim 30, wherein the data is asynchronously copied from the intermediate node to the secondary node.

36. The apparatus of claim 30, wherein the primary node provides data storage services over a network.

37. The apparatus of claim 30, wherein the secondary node provides data storage services over a network.

38. The apparatus of claim 30, wherein the secondary node is located at a site that is remote from a location of the primary node.

39. The apparatus of claim 30, wherein the intermediate node is located between the primary node and the secondary node.

40. The apparatus of claim 30, wherein direct communication is provided between the primary node and the secondary node when the intermediate node is not available for communication in the network.

41. The apparatus of claim 30, wherein the secondary node is configured to send a confirmation message to the intermediate node, in order to indicate that the data has been stored in the secondary node.

42. The apparatus of claim 41, wherein the intermediate node is configured to delete the data, in response to the confirmation message.

43. The apparatus of claim 30, wherein the intermediate node is configured to receive a first update from the primary node and a second update from the primary node;

and

wherein the secondary node is configured to receive the second update if the secondary node had previously received the first update.

44. The apparatus of claim 30, wherein the intermediate node is configured to receive a first update in a particular buffer space in the intermediate node and a second update in the particular buffer space in the intermediate node and to forward the second update to the secondary node.

45. The apparatus of claim 30, wherein the intermediate node is configured to define a time point from time t_A to time t_B, to batch all updates that are received by the intermediate node during the time point into an aggregated update, and to send the aggregated update to the secondary node.

46. An apparatus for tolerating network outages, the apparatus comprising:

a primary node;

a secondary node; and

an intermediate node configured to detect an occurrence of a network outage;

wherein the intermediate node is configured to store data that is received from the primary node, if the network outage is due to a failure between the intermediate node and the secondary node, or due to a failure of the secondary node;

wherein the primary node is configured to directly transmit the data to the secondary node, if the network outage is due to a failure between the primary node and the intermediate node, or due to a failure of the intermediate node.

47. The apparatus of claim 46, wherein the intermediate node is configured to transmit the stored data to the secondary node, after the failure between the intermediate node and the secondary node has been eliminated, or after the failure of the secondary node has been eliminated.

48. The apparatus of claim 46, wherein the secondary node is configured to store the data that is received from the intermediate node.

49. The apparatus of claim 46, wherein the secondary node is configured to store the data transmitted from the primary node.

50. An apparatus for data replication, the apparatus comprising:

a first primary node;

a second primary node;

a first secondary node;

a second secondary node; and

an intermediate node configured to receive data from the first primary node, to store the data in a first buffer space in the intermediate node, to forward the data to the first secondary node, to receive other data from the second primary node, to store the other data in a second buffer space in the intermediate node, and to forward the other data to the second secondary node.

51. The apparatus of claim 50, wherein the first secondary node is configured to store the data.

52. The apparatus of claim 50, wherein the second secondary node is configured to store the other data.

53. The apparatus of claim 50, wherein the data stored in the first buffer space is a subset of the data set that is stored in the first primary node.

54. The apparatus of claim 50, wherein the other data stored in the second buffer space is a subset of the data set that is stored in the second primary node.

55. The apparatus of claim 50, wherein the data is a copy of a data written to the first primary node.

56. The apparatus of claim 50, wherein the other data is a copy of a data written to the second primary node.