Preventing pauses in algorithms requiring pre-image information concerning modifications during data replication

• US 20100185585A1
• Filed: 01/09/2009
• Published: 07/22/2010
• Est. Priority Date: 01/09/2009
• Status: Active Grant

• Current Assignee: Pivotal Software, Inc. (Broadcom, Inc.)
• Original Assignee: GemStone Systems, Inc. (Broadcom, Inc.)
• Inventors: Schuchardt, Bruce J.
• Granted Patent: US 8,645,324 B2
• Time in Patent Office: Days
• US Class Current: 707/624
• CPC Class Codes: G06F 11/1658 Data re-synchronization of a redundant component, or initial sync of replacement, additional or spare unit
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• 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
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]

Abstract

Data accessible to a first process is replicated for use by a second process. Modifications to the data during the replication process may cause algorithms requiring the values of data both before and after replication to pause. Sending the values of the datum, before and after modification, to a process that will access the replicated data enables algorithms that use both values to initiate execution without waiting for the replication process to be completed.

Claims

1. A method of replicating data accessible to and alterable by a first process, said first process and a second process executing on a computing system, said method comprising the steps of:

(a) capturing data for copying;

(b) if a value of a captured datum is altered after said data is captured and before said captured data is copied, transmitting a copy of said captured datum and a copy of said altered value of said captured datum to said second process; and

(c) replicating said captured data for access by said second process.

2. The method of replicating data of claim 1 further comprising the step of updating said replicated data by replacing said captured datum with said altered value of said captured datum.

3. The method of replicating data of claim 1 further comprising the step of inputting said captured datum and said value of said altered value of said captured datum to an algorithm of said second process.

4. The method of replicating data of claim 1 further comprising the step of transmitting said altered value of said captured datum to a second replica of said data for use by a third process.

5. The method of replicating data of claim 1 wherein the step of replicating said captured data is performed after completion of all operations capable of altering said captured data undertaken before capture of said data by said first process and any other process capable of altering said captured data.

6. The method of replicating data of claim 5 wherein the step of replicating said captured data is performed after completion of all operations capable of altering said captured data undertaken before capture of said data by said first process and any other process capable of altering said captured data comprises the steps of:

(a) monitoring message transmission from said first process and any other process capable of altering said captured data to said data accessible to said first process;

(b) monitoring message receipt from said first process and any other process capable of altering said captured data; and

(c) replicating said data when a received message related to said captured data is as current as a transmitted message related to said captured data.

7. A method of replicating data accessible to a first process and alterable by at least said first process, said replica of said data accessible to a second process and alterable by at least said first process and said second process, said method comprising the steps of:

(a) capturing a portion of said data accessible to said first process to be copied;

(b) if a value of a datum included in said captured data is altered, transmitting said value of said altered datum to said first process, said second process and any other process capable of altering said value of said datum;

(c) transmitting a copy of said datum before alteration from said captured data to said second process;

(d) making said altered datum and said datum before alteration available to said second process for input to an algorithm of said second process;

(e) replicating said captured data; and

(f) replacing said datum in said captured data with said altered datum.

8. The method of replicating data of claim 7 wherein the step of replicating said captured data is performed after completion of all operations capable of altering said captured data undertaken before capture of said data by said first process and any other process capable of altering said captured data.

9. The method of replicating data of claim 8 wherein the step of replicating said captured data is performed after completion of all operations capable of altering said captured data undertaken before capture of said data by said first process and any other process capable of altering said captured data comprises the steps of:

(a) monitoring message transmission from said first process and any other process capable of altering said captured data to said data accessible to said first process;

(b) monitoring message receipt from said first process and any other process capable of altering said captured data; and

(c) replicating said data when a received message related to said captured data is as current as a transmitted message related to said captured data.

10. The method of replicating data of claim 7 wherein said data accessible to said first process is stored in first computer memory and said replica of said data is created in a second computer memory.

14. The computing system of claim 10 wherein said memory storing data accessible to said first process is accessible by a first processing unit and said portion of said memory accessible to said second process is accessible by a second processing unit.

15. The computing system of claim 10 further comprising:

(a) a first monitor tracking transmission of messages related to said captured data;

(b) a second monitor tracking receipt of messages related to said captured data; and

(c) a program instruction initiating replication of said captured data when a received message related to said captured data is as current as a transmitted message related to said captured data.

11. A computing system comprising:

(a) at least one processing unit for executing at least one of a first process and a second process;

(b) a memory storing data accessible by said first process and alterable by at least said first process, said data not accessible by said second process; and

(c) at least one program instruction executable by said processing unit enabling replication of a portion of said data in a portion of said memory accessible to said second process, said program instruction causing transmission of an unaltered value of a datum included in said data to be replicated and an altered value of said datum to said second process if said datum is altered after said data to be replicated is captured but before said captured data is replicated, said altered value of said datum and said unaltered value of said datum available to said second process before said data is replicated.

12. The computing system of claim 11 wherein said altered value of said data is stored in a portion of said memory accessible to said second process.

13. The computing system of claim 12 further comprising another program instruction causing said processing unit to replace said unaltered value of said datum in said replicated data with said altered value of said datum.