Synchronization of replicated sequential access storage components

• US 8,706,994 B2
• Filed: 01/17/2013
• Issued: 04/22/2014
• Est. Priority Date: 08/11/2009
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Akirav, Shay H., Bachar, Yariv, Drobchenko, Elena, Krikler, Samuel, Lazar, Aharon, Maoz, Itay, Melamed, Dan, Paz, Gil E.
• Primary Examiner(s): Verbrugge, Kevin
• Application Number:
  US13/743,791
• Publication Number:
  US 20130132343A1
• Time in Patent Office: 460 Days
• Field of Search: None
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor

Abstract

Various embodiments for synchronization of source and replicated instances of sequential access storage components in a computing environment by a processor device are provided. A replication synchronization table (RST) of a source instance is updated at a source component with the compacted information. Based on the RST of the source instance and the RST of the replicated instance, data representative of a most recent position on the source component from which data should be transmitted to a replicated component to achieve a full synchronization is determined.

Claims

1. A method for synchronization of source and replicated instances of sequential access storage components in a computing environment by a processor device, comprising:

updating a replication synchronization table (RST) of a source instance at a source component with compacted information; and

determining, based on the RST of the source instance and the RST of the replicated instance, data representative of a most recent position on the source component from which data should be transmitted to a replicated component to achieve a full synchronization.

2. The method of claim 1, further including configuring the replication synchronization table (RST) for the source instance, wherein the RST is adapted for recording compacted information for at least one of a truncate and an erase operation applied on the source instance.

3. The method of claim 2, further including, based on the data representative of the most recent position, synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect a synchronization status.

4. The method of claim 3, further including:

subsequent to the updating the RST of the source instance at the source component with the compacted information, transmitting the updated RST from the source instance to the replicated instance, and

subsequent to the determining the data representative of the most recent position on the source component, transmitting the data representative of the most recent position from the replicated instance to the source instance.

5. The method of claim 3, wherein the configuring the RST the source instance includes maintaining a current end of data (EOD) position for each of the source and replicated instances.

6. The method of claim 5, wherein the configuring the RST for the source instance includes configuring an entry in the RST to include fields for each of an operation identification value, a position value, and a unique system identification value.

7. The method of claim 6, wherein the updating the RST of the source instance at the source component with the compacted information includes:

for the at least one of the truncate and the erase operation, generating a new entry of the RST of the source instance,

if a write operation applies to a position smaller than the current EOD position for the source instance, determining the write operation to be the truncate operation,

appending the new entry to the RST of the source instance, and

if a first position value, based on the new entry, is one of smaller and equal to a second position value based on a most recent existing entry, removing all existing entries having position values one of larger and equal to the first position value.

8. The method of claim 7, wherein the generating the new entry further includes performing at least one of:

setting the first position value to a position in the new entry, and

setting a new unique system identification value of a generator of the new entry as a system identification in the new entry.

9. The method of claim 5, wherein the determining, based on the RST of the source instance and the RST of the replicated instance, the data representative of the most recent position on the source component from which the data should be transmitted to the replicated component to achieve the full synchronization includes:

locating a singular entry in the RST of the source instance at the source component having a maximum operation identification value of all entries in the RST having identical entries in the RST of the replicated instance at the replicated component,

if each of the singular entry and a succeeding entry in the RST of the source instance exists, and a succeeding entry of an identical entry of the singular entry in the RST of the replicated instance exists, calculating the most recent position as a first minimum value between a position value of the succeeding entry in the RST of the source instance, the current EOD position of the replicated instance, and a position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

10. The method of claim 9, wherein the determining further includes, if the succeeding entry in the RST of the identical entry of the replicated instance does not exist, calculating the most recent position as a second minimum value between the position value of the succeeding entry in the RST of the source instance and the current EOD position of the replicated instance.

11. The method of claim 10, wherein the determining further includes, if the singular entry exists and the succeeding entry in the RST of the source instance does not exist, and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance exists, calculating the most recent position as a third minimum value between the current EOD position of the replicated instance and the position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

12. The method of claim 11, wherein the determining further includes, if the singular entry exists and each of the succeeding entry in the RST of the source instance and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance does not exist, calculating the most recent position as the current EOD position of the replicated instance.

13. The method of claim 12, wherein the determining further includes, if the singular entry does not exist, calculating the most recent position as zero.

14. The method of claim 5, wherein the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status includes performing at least one of:

writing the data representative of the most recent position to a persistent storage location, and

advancing the current EOD position for the replicated instance.

15. The method of claim 14, wherein the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status further includes verifying the data representative of the most recent position using a mathematical digest.

16. The method of claim 14, wherein the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status further includes performing at least one of:

if the current EOD position for the replicated instance surpasses a first position value of the source instance, appending a new entry to the RST of the replicated instance such that each of an operation identification value, a position value, and a unique system identification value for the new entry of the RST of the replicated instance matches the new entry of the RST of the source instance, and

if the first position value of the source instance is one of smaller and equal to the second position value, removing all entries from the RST of the replicated instance having position values one of larger and equal to the first position value.

17. A system for synchronization of source and replicated instances of sequential access storage components in a computing environment, comprising:

at least one processor device operable in the computing environment, wherein the least one processor device;

updates a replication synchronization table (RST) of a source instance at a source component with compacted information; and

determines, based on the RST of the source instance and the RST of the replicated instance, data representative of a most recent position on the source component from which data should be transmitted to a replicated component to achieve a full synchronization.

18. The system of claim 17, wherein the least one processor device configures the replication synchronization table (RST) for the source instance, wherein the RST is adapted for recording compacted information for at least one of a truncate and an erase operation applied on the source instance.

19. The system of claim 18, wherein the least one processor device, based on the data representative of the most recent position, synchronizes the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect a synchronization status.

20. The system of claim 19, wherein the least one processor device:

subsequent to the updating the RST of the source instance at the source component with the compacted information, transmits the updated RST from the source instance to the replicated instance, and

subsequent to the determining the data representative of the most recent position on the source component, transmits the data representative of the most recent position from the replicated instance to the source instance.

21. The system of claim 19, wherein the least one processor device, pursuant to the configuring the RST for the source instance, maintains a current end of data (EOD) position for each of the source and replicated instances.

22. The system of claim 21, wherein the least one processor device, pursuant to the configuring the RST for the source instance, configures an entry in the RST to include fields for each of an operation identification value, a position value, and a unique system identification value.

23. The system of claim 22, wherein the least one processor device, pursuant to the updating the RST of the source instance at the source component with the compacted information:

for the at least one of the truncate and the erase operation, generates a new entry of the RST of the source instance,

if a write operation applies to a position smaller than the current EOD position for the source instance, determines the write operation to be the truncate operation,

appends the new entry to the RST of the source instance, and

if a first position value, based on the new entry, is one of smaller and equal to a second position value based on a most recent existing entry, removes all existing entries having position values one of larger and equal to the first position value.

24. The system of claim 23, wherein the least one processor device, pursuant to the generating the new entry, performs at least one of:

setting the first position value to a position in the new entry, and

setting a new unique system identification value of a generator of the new entry as a system identification in the new entry.

25. The system of claim 21, wherein the least one processor device, pursuant to the determining, based on the RST of the source instance and the RST of the replicated instance, the data representative of the most recent position on the source component from which the data should be transmitted to the replicated component to achieve the full synchronization:

locates a singular entry in the RST of the source instance at the source component having a maximum operation identification value of all entries in the RST having identical entries in the RST of the replicated instance at the replicated component,

if each of the singular entry and a succeeding entry in the RST of the source instance exists, and a succeeding entry of an identical entry of the singular entry in the RST of the replicated instance exists, calculates the most recent position as a first minimum value between a position value of the succeeding entry in the RST of the source instance, the current EOD position of the replicated instance, and a position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

26. The system of claim 25, wherein the least one processor device, pursuant to the determining, if the succeeding entry in the RST of the identical entry of the replicated instance does not exist, calculates the most recent position as a second minimum value between the position value of the succeeding entry in the RST of the source instance and the current EOD position of the replicated instance.

27. The system of claim 26, wherein the least one processor device, pursuant to the determining, if the singular entry exists and the succeeding entry in the RST of the source instance does not exist, and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance exists, calculates the most recent position as a third minimum value between the current EOD position of the replicated instance and the position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

28. The system of claim 27, wherein the least one processor device, pursuant to the determining, if the singular entry exists and each of the succeeding entry in the RST of the source instance and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance does not exist, calculates the most recent position as the current EOD position of the replicated instance.

29. The system of claim 28, wherein the least one processor device, pursuant to the determining, if the singular entry does not exist, calculating the most recent position as zero.

30. The system of claim 21, wherein the least one processor device, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, performs at least one of:

writing the data representative of the most recent position to a persistent storage location, and

advancing the current EOD position for the replicated instance.

31. The system of claim 30, wherein the least one processor device, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, verifies the data representative of the most recent position using a mathematical digest.

32. The system of claim 30, wherein the least one processor device, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, performs at least one of:

if the current EOD position for the replicated instance surpasses the first position value of the source instance, appending the new entry to the RST of the replicated instance such that each of the operation identification value, the position value, and the unique system identification value for the new entry of the RST of the replicated instance matches the new entry of the RST of the source instance, and

if the first position value of the source instance is one of smaller and equal to the second position value, removing all entries from the RST of the replicated instance having position values one of larger and equal to the first position value.

33. A non-transitory computer program product for synchronization of source and replicated instances of sequential access storage components in a computing environment by a processor device, the computer program product comprising a computer-readable storage medium having computer-readable program code portions stored therein, the computer-readable program code portions comprising:

a first executable portion that updates the RST of the source instance at a source component with the compacted information; and

a second executable portion that determines, based on the RST of the source instance and the RST of the replicated instance, data representative of a most recent position on the source component from which data should be transmitted to a replicated component to achieve a full synchronization.

34. The computer program product of claim 33, further including a third executable portion that configures the replication synchronization table (RST) for the source instance, wherein the RST is adapted for recording compacted information for at least one of a truncate and an erase operation applied on the source instance.

35. The computer program product of claim 34, further including a fourth executable portion that, based on the data representative of the most recent position, synchronizes the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect a synchronization status.

36. The computer program product of claim 35, further including a fifth executable portion that:

subsequent to the updating the RST of the source instance at the source component with the compacted information, transmits the updated RST from the source instance to the replicated instance, and

subsequent to the determining the data representative of the most recent position on the source component, transmits the data representative of the most recent position from the replicated instance to the source instance.

37. The computer program product of claim 35, further including a fifth executable portion that, pursuant to the configuring the RST for the source instance, maintains a current end of data (EOD) position for each of the source and replicated instances.

38. The computer program product of claim 37, further including a sixth executable portion that, pursuant to the configuring the RST for the source instance, configures an entry in the RST to include fields for each of an operation identification value, a position value, and a unique system identification value.

39. The computer program product of claim 38, further including a seventh executable portion that, pursuant to the updating the RST of the source instance at the source component with the compacted information:

for the at least one of the truncate and the erase operation, generates a new entry of the RST of the source instance,

if a write operation applies to a position smaller than the current EOD position for the source instance, determines the write operation to be the truncate operation,

appends the new entry to the RST of the source instance, and

if a first position value, based on the new entry, is one of smaller and equal to a second position value based on a most recent existing entry, removes all existing entries having position values one of larger and equal to the first position value.

40. The computer program product of claim 39, further including an eighth executable portion that, pursuant to the generating the new entry, performs at least one of:

setting the first position value to a position in the new entry, and

setting a new unique system identification value of a generator of the new entry as a system identification in the new entry.

41. The computer program product of claim 37, further including a sixth executable portion that, pursuant to the determining, based on the RST of the source instance and the RST of the replicated instance, the data representative of the most recent position on the source component from which the data should be transmitted to the replicated component to achieve the full synchronization:

locates a singular entry in the RST of the source instance at the source component having a maximum operation identification value of all entries in the RST having identical entries in the RST of the replicated instance at the replicated component,

if each of the singular entry and a succeeding entry in the RST of the source instance exists, and a succeeding entry of an identical entry of the singular entry in the RST of the replicated instance exists, calculates the most recent position as a first minimum value between a position value of the succeeding entry in the RST of the source instance, the current EOD position of the replicated instance, and a position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

42. The computer program product of claim 41, further including a seventh executable portion that, pursuant to the determining, if the succeeding entry in the RST of the identical entry of the replicated instance does not exist, calculates the most recent position as a second minimum value between the position value of the succeeding entry in the RST of the source instance and the current EOD position of the replicated instance.

43. The computer program product of claim 42, further including an eighth executable portion that, pursuant to the determining, if the singular entry exists and the succeeding entry in the RST of the source instance does not exist, and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance exists, calculates the most recent position as a third minimum value between the current EOD position of the replicated instance and the position value of the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance.

44. The computer program product of claim 43, further including a ninth executable portion that, pursuant to the determining, if the singular entry exists and each of the succeeding entry in the RST of the source instance and the succeeding entry of the identical entry of the singular entry in the RST of the replicated instance does not exist, calculates the most recent position as the current EOD position of the replicated instance.

45. The computer program product of claim 44, further including a tenth executable portion that, pursuant to the determining, if the singular entry does not exist, calculating the most recent position as zero.

46. The computer program product of claim 37, further including a sixth executable portion that, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, performs at least one of:

writing the data representative of the most recent position to a persistent storage location, and

advancing the current EOD position for the replicated instance.

47. The computer program product of claim 46, further including a seventh executable portion that, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, verifies the data representative of the most recent position using a mathematical digest.

48. The computer program product of claim 46, further including a seventh executable portion that, pursuant to the synchronizing the replicated instance with the source instance while updating the RST of the replicated instance with the data representative of the most recent position to reflect the synchronization status, performs at least one of:

if the current EOD position for the replicated instance surpasses the first position value of the source instance, appending the new entry to the RST of the replicated instance such that each of the operation identification value, the position value, and the unique system identification value for the new entry of the RST of the replicated instance matches the new entry of the RST of the source instance, and

if the first position value of the source instance is one of smaller and equal to the second position value, removing all entries from the RST of the replicated instance having position values one of larger and equal to the first position value.