System and method for verifying and correcting the consistency of mirrored data sets

• US 8,010,509 B1
• Filed: 06/30/2006
• Issued: 08/30/2011
• Est. Priority Date: 06/30/2006
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Khurana, Varun, Malaiyandi, Prasanna Kumar
• Primary Examiner(s): Mofiz; Apu M
• Assistant Examiner(s): Bibbee; Jared M
• Application Number:
  US11/478,931
• Time in Patent Office: 1,887 Days
• Field of Search: 707/10, 707/201, 707/690, 707/691, 707/697, 714/5
• US Class Current: 707/690
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2082 Data synchronisation

Abstract

A system and method verifies and repairs mirrored data sets. Verification modules executing on both the source and destination computers cooperate to identify a common persistent consistency point image (PCPI) of the source and destination data sets. Once the common image has been identified, the source sends a data stream comprising the data from the source data set to the destination to be compared with the destination data set.

Claims

1. A method for verifying that first and second data sets are consistent comprising:

identifying, by a processor, a common instantiation of the first and second data sets, the first data set associated with a source verification module and the second data set associated with a destination verification module;

utilizing the identified common instantiation to perform a verification process between the source verification module and the destination verification module, wherein the source verification module and the destination verification module perform the verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks;

sending, from a source computer hosting the first data set, a data stream associated with the first data set to a destination computer hosting the second data set;

comparing, at the destination computer, the received data stream with the second data set; and

in response to detecting one or more data inconsistencies between the received data stream and the second data set, generating, by the processor, a verify log configured to record the one or more data inconsistencies on a persistent storage device, the verify log utilized by the destination computer to notify an administrator of the inconsistencies.

2. The method of claim 1 wherein the data stream comprises all blocks of data in the first data set.

3. The method of claim 1 wherein the data stream comprises checksum information associated with the first data set.

4. The method of claim 1 further comprising:

sending the verify log to the source computer hosting the first data set; and

sending, from the source computer hosting the first data set, a data stream comprising blocks identified in the verify log.

5. The method of claim 4 further comprising updating the second data set using the blocks identified in the verify log.

6. The method of claim 1 wherein the first and second data sets comprise file systems.

7. The method of claim 1 wherein the first and second data sets comprise persistent consistency point images.

24. The method of claim 1 wherein the common instantiation of the first and second data sets comprises a most recent persistent consistency point image common to both the first data set and the second data set.

8. A computer readable medium, including program instructions executing on a computer, for verifying that first and second data sets are consistent, the computer readable medium including instructions for performing:

identifying, by a processor, a common instantiation of the first and second data sets, the first data set associated with a source verification module and the second data set associated with a destination verification module;

utilizing the identified common instantiation to perform a verification process between the source verification module and the destination verification module, wherein the source verification module and the destination verification module perform the verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks;

sending, from a source computer hosting the first data set, a data stream associated with the first data set to a destination computer hosting the second data set;

comparing, at the destination computer, the data stream with the second data set; and

in response to detecting one or more data inconsistencies between the received data stream and the second data set, generating, by the processor, a verify log configured to record the one or more data inconsistencies on a persistent storage device, the verify log utilized by the destination computer to notify an administrator of the inconsistencies.

9. A system configured to verify that first and second data sets are consistent comprising:

a source computer serving the first data set and executing a source verification module;

a destination computer serving the second data set and executing a destination verification module, wherein the destination verification module sends an identifier of a common instantiation of the first and second data sets to the source verification module; and

wherein the source verification module transmits a data stream associated with the identified instantiation of the first data set to the destination verification module, and wherein the destination verification module;

compares the data stream with the second data set, and

in response to one or more data inconsistencies between the data stream and the second data set, generates a verify log configured to record the one or more data inconsistencies on a persistent storage device, the verify log utilized by the destination computer to notify an administrator of the inconsistencies; and

wherein the source verification module and the destination verification module perform a verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks.

10. The system of claim 9 wherein the data stream comprises all blocks of data in the first data set.

11. The system of claim 9 wherein the data stream comprises checksum information associated with the first data set.

12. The system of claim 11 wherein the checksum information comprises RAID checksums.

13. The system of claim 9 wherein the first and second data sets comprise file systems.

14. The system of claim 9 wherein the first and second data sets comprise persistent consistency point images.

15. The system of claim 9 wherein the identified instantiation of the first data set comprises a persistent consistency point image.

16. A system comprising:

a source storage system having a first computer with a first processor and one or more persistent consistency point images (PCPIs);

a destination storage system having a second computer with a second processor and one or more PCPIs, the source storage system having a first PCPI, the destination storage system having a second PCPI, where the first and second PCPIs are in common with each other;

a source verification module executing on the source storage system, the source verification module configured to transmit the first PCPI to the destination storage system; and

a destination verification module executing on the destination storage system, the destination verification module configured to;

compare the first and second PCPIs;

in response to detecting one or more inconsistencies between the first and second PCPIs, update the destination storage system to render the second PCPI consistent with the first PCPI and generate a verify log configured to record the one or more data inconsistencies on a persistent storage device, the verify log utilized by the destination computer to notify an administrator of the inconsistencies; and

wherein the source verification module and the destination verification module perform a verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks.

17. The system of claim 16 further comprising:

a baseline PCPI of the source storage system, the source storage system further configured to transmit the baseline PCPI to the destination storage system;

a next PCPI of the source storage system, the next PCPI generated by the source storage system after the destination storage system has received the baseline PCPI; and

a mirroring application module of the source storage system, the mirroring application module configured to determine one or more changes between the baseline PCPI and the next PCPI and transmit only the one or more changes to the destination storage system.

18. The system of claim 17 wherein the destination storage system is further configured to receive the changes and generate a next PCPI such that the baseline and next PCPIs on both the source storage system and the destination storage system are identical.

19. The system of claim 16 further comprising:

a verification module for verifying the consistency of the source storage system and the destination storage system; and

an administrator configured to invoke the verification module.

20. The system of claim 19 wherein the verification module is automatically invoked.

21. A method comprising:

determining, by a source and destination storage system, a most recent persistent consistency point image (PCPI) common to both the source and the destination storage system, the source storage system having a first PCPI, the destination storage system having a second PCPI, where the first and second PCPIs are in common with each other, the first PCPI associated with a source verification module and the second PCPI associated with a destination verification module;

utilizing the identified most recent PCPI to perform a verification process between the source verification module and the destination verification module wherein the source verification module and the destination verification module perform the verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks;

transmitting the first PCPI to the destination storage system;

receiving the first PCPI at the destination storage system;

comparing the first PCPI with the second PCPI; and

in response to one or more data mismatches between the first and second PCPIs, correcting, by the destination storage system, the second PCPI so that the first and second PCPIs are consistent and generate a verify log configured to record the one or more data inconsistencies on a persistent storage device, the verify log utilized by the destination computer to notify an administrator of the inconsistencies.

22. The method of claim 21 further comprising:

transmitting, to the destination storage system, one or more additional PCPIs of the source storage system, the one or more additional PCPIs of the source storage system older than first and second PCPIs;

receiving the one or more additional PCPIs of the source storage system at the destination storage system;

comparing each of the one or more additional PCPIs of the source storage system with an additional PCPI of the destination storage system; and

in response to one or more data mismatches between at least one of the one or more additional PCPIs of the source storage system and at least one additional PCPI of the destination storage system, correcting, by the destination storage system one or more additional PCPIs of the destination storage system so that the additional PCPIs of the source and destination storage systems are consistent.

23. The method of claim 22 further comprising transmitting, to the destination storage system, a data stream, the data stream comprising the first PCPI and the one or more additional PCPIs of the source storage system.

25. A method comprising:

identifying a most recent persistent consistency point image (PCPI) common to both a source storage system and a destination storage system, a first PCPI associated with a source verification module and a second PCPI associated with a destination verification module;

utilizing the identified most recent PCPI to perform a verification process between the source verification module and the destination verification module wherein the source verification module and the destination verification module perform the verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks;

transmitting a data stream from the source storage system to the destination storage system, the data stream comprising data blocks of a source storage system version of the identified most recent PCPI common to the source and destination storage systems;

receiving the data stream at the destination storage system;

performing, by the destination storage system, a verification procedure to identify one or more data mismatches between the data blocks of the data stream and data blocks of the destination storage system; and

in response to identifying one or more data mismatches, generating, by the destination storage system, a verify log of the one or more data mismatches, the verify log utilized by the destination computer to notify an administrator of the data mismatches.

26. The method of claim 25 wherein the verification procedure comprises comparing the data blocks of the data stream with data blocks of a destination storage system version of the identified most recent PCPI common to the source and destination storage systems.

27. The method of claim 26 wherein data blocks are compared on a byte-by-byte basis.

28. The method of claim 25 wherein the data stream further comprises data blocks of any PCPI of the source storage system older than the identified most recent PCPI common to the source and destination storage systems.

29. The method of claim 25 wherein the data stream further comprises a list of one or more PCPIs with which the data blocks of the data stream are associated.

30. The method of claim 29 further comprising recording the list of one or more PCPIs with which the data blocks of the data stream are associated in the verify log.

31. The method of claim 25 further comprising, in response to an initiation by an administrator, utilizing the verify log to perform a repair procedure.

32. The method of claim 31 wherein the repair procedure comprises updating the data blocks of the destination storage system to render the data blocks of the source and destination storage systems consistent.

33. The method of claim 31 wherein the initiation is configured to occur automatically.

34. The method of claim 25 wherein the verification log comprises a list of one or more block numbers in which the one or more data mismatches occurred.

35. A system comprising:

a source storage system having a first computer with a source processor and one or more persistent consistency point images (PCPIs);

a destination storage system having a second computer with a destination processor and one or more PCPIs, the source storage system and the destination storage system having in common a most recent PCPI of the one or more PCPIs of the source and destination storage systems;

a source verification module executing on the source storage system, the source verification module configured to transmit a data stream from the source storage system to the destination storage system, the data stream comprising data blocks of a source storage system version of the identified most recent PCPI common to the source and destination storage systems; and

a destination verification module executing on the destination storage system, the destination verification module configured to;

perform a verification procedure to identify one or more data mismatches between the data blocks of the data stream and data blocks of the destination storage system;

in response to identifying one or more data mismatches, generate a verify log of the one or more data mismatches, the verify log utilized by the destination computer to notify an administrator of the mismatches; and

wherein the source verification module and the destination verification module perform a verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks.

36. A method comprising:

identifying a most recent persistent consistency point image (PCPI) common to both a source storage system and a destination storage system, a first PCPI associated with a source verification module and a second PCPI associated with a destination verification module;

utilizing the identified most recent PCPI to perform a verification process between the source verification module and the destination verification module wherein the source verification module and the destination verification module perform the verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks;

transmitting a data stream from the source storage system to the destination storage system, the data stream comprising checksums of data blocks of a source storage system version of the identified most recent PCPI common to the source and destination storage systems;

receiving the data stream at the destination storage system;

performing, by the destination storage system, a verification procedure to identify one or more data mismatches between the checksums of the data stream and checksums of data blocks of the destination storage system; and

in response to identifying one or more data mismatches, generating, by the destination storage system, a verify log of the one or more data mismatches, the verify log utilized by the destination computer to notify an administrator of the mismatches.

37. A system comprising:

a source storage system having a first computer with a first processor and one or more persistent consistency point images (PCPIs);

a destination storage system having a second computer with a second processor and one or more PCPIs, the source storage system and the destination storage system having in common a most recent PCPI of the one or more PCPIs of the source and destination storage systems;

a source verification module executing on the source storage system, the source verification module configured to transmit a data stream from the source storage system to the destination storage system, the data stream comprising checksums of data blocks of a source storage system version of the identified most recent PCPI common to the source and destination storage systems; and

a destination verification module executing on the destination storage system, the destination verification module configured to;

perform a verification procedure to identify one or more data mismatches between the checksums of the data stream and checksums of data blocks of the destination storage system;

in response to identifying one or more data mismatches, generate a verify log of the one or more data mismatches, the verify log utilized by the destination computer to notify an administrator of the mismatches

wherein the source verification module and the destination verification module perform a verification process using a plurality of different modes, the plurality of different modes including a first mode, a second mode, and a third mode,

wherein the first mode performs a combined verification and repair procedure, the second mode performs only a verification procedure, and the third mode operates in combination with either the first mode or the second mode to send checksum information over a network in place of complete data blocks.