Parallel replication mechanism for state information produced by serialized processing

• US 20020161789A1
• Filed: 03/20/2002
• Published: 10/31/2002
• Est. Priority Date: 03/21/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation, SAP AG (SAP SE)
• Original Assignee: SAP AG (SAP SE)
• Inventors: Reichert, Wolfgang, Schaefer, Christian, Schmidt, Lutz
• Granted Patent: US 7,533,132 B2
• Time in Patent Office: Days
• US Class Current: 707/203
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1666 where the redundant component is memory or memory area
• CPC Class Codes: G06F 11/20 using active fault-masking, e.g. by switching out faulty elements or by switching in spare elements
• CPC Class Codes: G06F 11/3055 Monitoring arrangements for monitoring the status of the computing system or of the computing system component, e.g. monitoring if the computing system is on, off, available, not available error or fault processing without redundancy G06F11/0703; error detection or correction by redundancy in data representation G06F11/08; error detection or correction by redundancy in operation G06F11/14; error detection or correction by redundancy in hardware G06F11/16

Abstract

A method and system that replicates state information stored in a first data processing system to a second data processing system, whereby the state information is kept in a set of records. An incoming request message requesting a change of the state information is received and an indicator is assigned to the incoming request message representing the order in which the incoming request messages are processed. The sender of the incoming request message is sent a response message after confirmation that the at least one first storage subsystem received a modification record containing the indicator for the incoming request message and modification records of all predecessors of the incoming request message. The at least one first storage subsystem may send an acknowledge message to the first data processing unit confirming receipt of a modification record.

Claims

1. A method for parallel replication of state information of a first data processing unit in at least one second data processing unit, each of the at least one second data processing units having a replica of the state information of the first data processing unit, the method comprising:

processing an incoming request message for changing the state information in the first data processing unit;

sending a response message to a sender of the incoming request message after confirming a receipt of a modification record for the incoming request message and modification records of all predecessors of the incoming request message by each of the at least one first storage subsystems; and

updating state information in the replica of each of the at least one second data processing units based on the modification records,

wherein the incoming request message contains an indicator and a modification record contains the indicator assigned to a corresponding incoming request message and all corresponding changes applied to a set of records used to represent the state information of the first data processing unit.

2. The method of claim 1, wherein the indicator of an incoming request message represents an order in which the incoming request message is to be processed.

3. The method of claim 1, wherein the at least one first storage subsystem resides on the at least one second data processing unit.

4. The method of claim 1, wherein an acknowledge message is sent from the at least one first storage subsystem to the first data processing unit to confirm a receipt of a modification record.

5. The method of claim 1, wherein the first data processing unit is capable of concurrently sending a plurality of modification messages to each of the at least one first storage subsystems.

6. A system for parallel replication of state information of a first data processing unit in at least one second data processing unit, each of the at least one second data processing units having a replica of the state information of the first data processing unit, the system comprising:

a first processing unit for processing an incoming request message for changing the state information in the first data processing unit;

a respond unit for sending a response message to a sender of the incoming request message after confirming a receipt of a modification record for the incoming request message and modification records of all predecessors of the incoming request message by each of the at least one first storage subsystems; and

at least one second processing unit for updating state information in the replica of each of the at least one second data processing units based on the modification records,

wherein an incoming request message contains an indicator and a modification record contains the indicator assigned to a corresponding incoming request message and all corresponding changes applied to a set of records used to represent the state information of the first data processing unit.

7. The system of claim 6, wherein the indicator of an incoming request message represents an order in which the incoming request message is to be processed.

8. The system of claim 6, wherein the at least one first storage subsystem resides on the at least one second data processing unit.

9. The system of claim 6, wherein an acknowledge message is sent from the at least one first storage subsystem to the first data processing unit to confirm a receipt of a modification record.

10. The system of claim 6, wherein the first data processing unit is capable of concurrently sending a plurality of modification messages to each of the at least one first storage subsystems.

11. A system for parallel replication of state information of a first data processing unit in at least one second data processing unit, each of the at least one second data processing units having a replica of the state information of the first data processing unit, the system comprising:

means for processing an incoming request message for changing the state information in the first data processing unit;

means for sending a response message to a sender of the incoming request message after confirming a receipt of a modification record for the incoming request message and modification records of all predecessors of the incoming request message by each of the at least one first storage subsystems; and

means for updating state information in the replica of each of the at least one second data processing units based on the modification records,

wherein an incoming request message contains an indicator and a modification record contains the indicator assigned to a corresponding incoming request message and all corresponding changes applied to a set of records used to represent the state information of the first data processing unit.

13. The method according to claim 12, wherein receiving an incoming request message, assigning an indicator, processing the incoming request message and sending a modification record are performed concurrently to checking acknowledge messages and sending a response message.

14. The method according to claim 12, wherein sending the modification record to the first storage subsystem is performed concurrently with sending other modification records to the first storage subsystem.

15. The method according to claim 12, wherein the first storage subsystem is provided on the second data processing unit, the first and the second data processing units are connected to each other with more than one communication channel and the method further comprises storing all modification records into the first storage subsystem on the second data processing unit.

16. The method according to claim 15, wherein the first storage subsystem is configured to be able to receive all modification records at the same time which are concurrently sent by the first data processing unit and the method further comprises concurrently storing all modification records into the first storage subsystem.

17. The method according to claim 12, wherein the second data processing unit comprises a second storage subsystem for storing the replicated set of records and the method further comprises applying the changes indicated by the modification record stored in the first storage subsystem to the set of records stored in the second storage subsystem.

18. The method according to claim 17, wherein each record stored in the second storage subsystem includes a field for storing the indicator and applying the changes includes storing the indicator assigned to the processed request message in the respective field of all changed records.

19. The method according to claim 17, wherein applying changes includes checking the indicator and only modifications more recent than the last change applied to a particular record are applied.

20. The method according to claim 15, further comprising returning an acknowledge message to the first data processing unit indicating a receipt of a particular modification record after it has been stored in the first storage subsystem.

21. The method according to claim 12, wherein each record includes a field for storing the indicator and updating the set of records includes storing the indicator assigned to the processed request message in the respective field of all changed records.

22. The method according to claim 12, wherein receiving an incoming request for changing the state information is followed by determining the next incoming request to serve, in case more than one incoming request is waiting to be processed.

24. The system according to claim 23, wherein the first storage subsystem is formed on the second data processing unit.

25. The system according to claim 23, wherein the first data processing unit and the second data processing unit are connected to each other with more than one communication channel to allow concurrent transmission of modification records to the first storage subsystem on the second data processing unit.

26. The system according to claim 23, wherein the first storage subsystem is configured to be able to receive and store all modification records at the same time which are concurrently sent by the first data processing unit.

27. The system according to claim 23, wherein the second data processing unit comprises a second storage subsystem for storing the replicated set of records and a second processing unit for applying the changes indicated by the modification records stored in the first storage subsystem to the set of records stored in the second storage subsystem.

28. The system according to claim 27, wherein each record stored in the second storage subsystem includes a field for storing the indicator and the second processing unit is configured to store the indicator assigned to the processed request message in the respective field of all changed records when applying changes.

29. The system according to claim 27, wherein the second processing unit is further configured to check the indicator and to only apply modifications which are more recent than the last change applied to a particular record.

30. The system according to claim 25, further comprising an acknowledge unit for returning an acknowledge message to the first data processing unit indicating a receipt of a particular modification record after it has been stored in the first storage subsystem.

31. The system according to claim 23, wherein each record includes a field for storing the indicator and the first processing unit is configured to store the indicator assigned to the processed request message in the respective field of all changed records.

32. The system according claim 23, wherein the initializing unit is further configured to determine the next incoming request to serve, in case more than one incoming request is waiting to be processed.

12. A method for replicating state information stored in a first data processing unit to a second data processing unit, whereby the state information is kept in a set of records, the method comprising, for each incoming request message

requesting a change of the state information:

receiving an incoming request message for changing the state information;

assigning an indicator to the incoming request message representing the order in which the incoming request messages are processed;

processing the incoming request message and updating the set of records in accordance with the result of the processing of the incoming request message;

sending a modification record to a first storage subsystem containing the indicator assigned to the incoming request message and all changes applied to the set of records performed during processing of the incoming request message;

checking acknowledge messages which have been received from the second data processing unit indicating a receipt of the sent modification records; and

sending a response message as a reaction to an incoming request message to the respective sender for such incoming request messages, the modification record of which and the modification records of all its predecessors having been received by the first storage subsystem.

23. A system for replicating state information stored in a first data processing unit to a second data processing unit, whereby the state information is kept in a set of records, the system comprising:

an input port for receiving an incoming request message for changing the state information;

an initializing unit for assigning an indicator to the incoming request message representing the order in which the incoming request messages will be processed;

a first processing unit for processing the incoming request message and updating the set of records in accordance with the result of the processing of the incoming request message;

a communication unit for sending a modification record to a first storage subsystem containing the indicator assigned to the incoming request message and all changes applied to the set of records performed during processing of the incoming request message;

a control unit for checking acknowledge messages which have been received from the first storage subsystem indicating a receipt of the sent modification records; and

a respond unit for sending a response message as a reaction to an incoming request message to the respective sender for such incoming request messages, the modification record of which and the modification records of all its predecessors having been received by the second data processing unit.

33. A computer program product stored on a computer usable medium, comprising computer readable program means for causing a computer to perform a method for replicating state information stored in a first data processing unit to a second data processing unit, whereby the state information are kept in a set of records, the method comprising:

receiving an incoming request message for changing the state information;

assigning an indicator to the incoming request message representing the order in which the incoming request messages are processed;

processing the incoming request message and updating the set of records in accordance with the result of the processing of the incoming request message;

sending a modification record to a first storage subsystem containing the indicator assigned to the incoming request message and all changes applied to the set of records performed during processing of the incoming request message;

checking acknowledge messages which have been received from the second data processing unit indicating a receipt of the sent modification records; and

sending a response message as a reaction to an incoming request message to the respective sender for such incoming request messages the modification record of which and the modification records of all its predecessors have been received by the first storage subsystem.

34. The computer program product according to claim 33, wherein the steps of receiving an incoming request message, assigning an indicator, processing the incoming request message and sending a modification record are performed concurrently to the steps of checking acknowledge messages and sending a response message.

35. The computer program product according to claim 33, wherein sending modification record to the first storage subsystem is performed concurrently with sending other modification records to the first storage subsystem.

36. The computer program product according to claim 33, wherein the first storage subsystem is provided on the second data processing unit, the first and the second data processing unit are connected to each other with more than one communication channel and the method further comprises storing all modification records into the first storage subsystem on the second data processing unit.

37. The computer program product according to claim 36, wherein the first storage subsystem is configured to be able to receive all modification records at the same time which are concurrently sent by the first data processing unit and the method further comprises concurrently storing all modification records into the first storage subsystem.

38. The computer program product according to claim 33, wherein the second data processing unit comprises a second storage subsystem for storing the replicated set of records and the method further comprises applying the changes indicated by the modification record stored in the first storage subsystem to the set of records stored in the second storage subsystem.

39. The computer program product according to claim 38, wherein each record stored in the second storage subsystem includes a field for storing the indicator and applying the changes includes storing the indicator assigned to the processed request message in the respective field of all changed records.

40. The computer program product according to claim 38, wherein applying changes includes checking the indicator and only modifications more recent than the last change applied to a particular record are applied.

41. The computer program product according to claim 36, further comprising returning an acknowledge message to the first data processing unit indicating a receipt of a particular modification record after it has been stored in the first storage subsystem.

42. The computer program product according to claim 33, wherein each record includes a field for storing the indicator and updating the set of records includes storing the indicator assigned to the processed request message in the respective field of all changed records.

43. The computer program product according to claim 33, wherein receiving an incoming request for changing the state information is followed by determining the next incoming request to serve, in case more than one incoming request is waiting to be processed.