Data replication method

• US 20090119347A1
• Filed: 11/02/2007
• Published: 05/07/2009
• Est. Priority Date: 11/02/2007
• Status: Active Grant

• Current Assignee: Pivotal Software, Inc. (Broadcom, Inc.)
• Original Assignee: GemStone Systems, Inc. (Broadcom, Inc.)
• Inventors: Schuchardt, Bruce J.
• Granted Patent: US 8,005,787 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 16/275 Synchronous replication
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

To ensure data consistency for a new data replica created for a computing system, the transmission and receipt of messages altering the data are monitored and replication of the data is permitted when all changes to the data that have been transmitted to the data have been received.

Claims

1. A method of replicating a datum in a first process executed by a computing system, said datum held by a second process and alterable by a third process, said method comprising the step of enabling replication of said datum in said first process when a message received from a communication channel enabling alteration of said datum is at least as current as a message transmitted over said communication channel.

2. The method of replicating a datum of claim 1 wherein the step of enabling replication of said datum when said message received from said communication channel enabling alteration of said datum is at least as current as said message transmitted over said communication channel comprises the step counting a number of messages received from said communication channel.

3. The method of replicating a datum of claim 1 wherein the step of enabling replication of said datum when said message received from said communication channel enabling alteration of said datum is at least as current as said message transmitted over said communication channel comprises the step counting a number of messages transmitted over said communication channel.

4. The method of replicating a datum of claim 1 wherein the step of enabling replication of said datum in said first process when a message received from a communication channel enabling alteration of said datum is at least as current as a message transmitted over said communication channel comprises the steps of:

(a) comparing a number of messages transmitted to said datum over said communication channel to a number of messages received by said datum from said communication channel; and

(b) when said number of messages received is at least equal to said number of messages transmitted, enabling said datum to be replicated in said first process.

5. A method of replicating a datum in a first process executed by a computing system, said datum held by a second process and alterable by a message received over one of a first communication channel and a second communication channel, said method comprising the step of:

(a) determining a currency of a message transmitted over said first communication channel;

(b) determining a currency of a message received from said first communication channel;

(c) determining a currency of a message transmitted over said second communication channel;

(d) determining a currency of a message received from said second communication channel; and

(e) enabling replication of said datum in said first process when said message received from said first communication channel is at least as current as said message transmitted over said first communication channel and said message received from said second communication channel is at least as current as said message transmitted over said second communication channel.

6. The method of replicating a datum of claim 5 wherein said first communication channel communicatively interconnects a third process and said datum and said second communication channel communicatively interconnects a fourth process and said datum.

7. The method of replicating a datum of claim 5 wherein said first communication channel and said second communication channel communicatively interconnect a third process and said datum.

8. The method of replicating a datum of claim 5 wherein a number of messages transmitted to said datum over one of said first and said second communication channels is a measure of said currency of said message.

9. The method of replicating a datum of claim 5 wherein a number of messages received by said datum from one of said first and said second communication channels is a measure of said currency of said message.

10. The method of replicating a datum of claim 5 wherein the step of enabling replication of said datum in said first process when said message received from said first communication channel is at least as current as said message transmitted over said first communication channel and said message received from said second communication channel is at least as current as said message transmitted over said second communication channel comprises the steps of:

(a) comparing a number of messages transmitted to said datum over said first communication channel to a number of messages received by said datum from said first communication channel;

(b) comparing a number of messages transmitted to said datum over said second communication channel to a number of messages received by said datum from said second communication channel; and

(c) enabling replication of said datum in said first process when said number of messages received from said first communication channel is at least equal to said number of messages transmitted over said first communication channel and said number of messages received from said second communication channel is at least equal to said number of messages transmitted over said second communication channel.

11. A method of replicating a datum in a first process executed by a computing system, said datum held by a second process and alterable by a message received by said datum, said method comprising the steps of:

(a) identifying a first communication channel enabling a message altering said datum to be communicated to said datum;

(b) determining a number of messages transmitted to said datum over said first communication channel;

(c) determining a number of messages received by said datum from said first communication channel;

(d) comparing said number of said messages received from said first communication channel to said number of messages transmitted over said first communication channel;

(e) notifying said first process that all alterations transmitted to said datum over said first communication channel have been received; and

(f) enabling replication of said datum in said first process when all alterations of said datum transmitted to said datum have been received.

12. The method of replicating a datum of claim 11 further comprising the step of transmitting an alteration of said datum to said datum and to said first process if said alteration is undertaken after receipt of a notice of intent to replicate said datum.

13. The method of replicating a datum of claim 11 further comprising the steps of:

(a) identifying a second communication channel enabling a message altering said datum to be communicated to said datum;

(b) determining a number of messages transmitted to said datum over said second communication channel;

(c) determining a number of messages received by said datum from said second communication channel;

(d) comparing said number of said messages received from said second communication channel to said number of messages transmitted over said second communication channel; and

(e) notifying said first process that all alterations transmitted to said datum over said second communication channel have been received.

14. The method of replicating a datum of claim 13 wherein an alteration of said datum by a third process is transmitted to said datum over one of said first and said second communication channels.

15. The method of replicating a datum of claim 14 further comprising the step of transmitting an alteration of said datum to said datum and to said first process if said alteration is undertaken after receipt of a notice of intent to replicate said datum.

16. The method of replicating a datum of claim 13 wherein an alteration of said datum by a third process is communicated to said datum over said first communication channel and an alteration of said datum by a fourth process is communicated to said datum over said second communication channel.

17. The method of replicating a datum of claim 16 further comprising the step of transmitting an alteration of said datum to said datum and to said first process if said alteration is undertaken by one of said third process and said fourth process after receipt of a notice of intent to replicate said datum.