System for synchronizing replicas of a database

• US 7,725,766 B2
• Filed: 06/12/2008
• Issued: 05/25/2010
• Est. Priority Date: 03/10/2005
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Varghese, John
• Primary Examiner(s): Puente; Emerson C
• Application Number:
  US12/138,003
• Publication Number:
  US 20080244334A1
• Time in Patent Office: 712 Days
• Field of Search: 714/6
• US Class Current: 714/4.4
• 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 16/273 Asynchronous replication or reconciliation
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes

Abstract

A system for synchronizing replicas of a database. The system detects a failure of update data from a first replica to be applied to a second replica and determines a cause of the failure. The system also resolves the cause of the failure. According to the system disclosed herein, the present invention synchronizes the replicas of the database without requiring manual intervention.

Claims

1. A database system comprising:

a first server site comprising a first replica of a database;

a second server site coupled to the first server site, the second server site comprising a second replica of the database; and

a client coupled to the first replica wherein the client is operable to;

send update data from a first replica to a second replica, the first replica being associated with a first acquire server unit and a first acquire client unit, the second replica being associated with a second acquire server unit and a second acquire client unit;

automatically detect a failure of the update data from the first replica to be applied to the second replica wherein the detecting comprises;

requesting, by the first acquire client unit from the second acquire server unit, metadata comprising export parameters; and

receiving, by the first acquire client unit from the second acquire server unit, the metadata;

automatically determine a cause of the failure and where the cause of failure occurred, wherein the determining comprises;

determining, by the first acquire client unit, if the failure was due to a packet being lost, wherein the packet contains the update data, wherein the first acquire client unit determines if the failure was due to a packet being lost by requesting from the second acquire server unit, the result of the last failed import to confirm that the packet was actually lost;

parsing, by the first acquire client, the metadata received from the second acquire server unit, wherein the parsed metadata indicates if an account is locked out; and

determining, by the first acquire client unit, if the second replica is updated with current update data;

automatically resolve the cause of the failure, wherein the resolving comprises;

requesting, by the first acquire client unit, for a packet to be resent if the cause of the failure is due to the packet being lost;

resending, by the first acquire client unit, a packet containing the update data if the second replica is not updated with current update data;

unlocking, by the first acquire client unit, an account if the cause of the failure is due to the account being locked out;

deleting, by the first acquire client unit, an object if the cause of the failure is due to the object not being deleted during a previous export;

notifying, by the first acquire client unit, an appropriate authority of the failure if corrective actions need to be taken by the appropriate authority;

resending the update data;

applying the update data to the second replica; and

recording update data in an operations log.

2. The system of claim 1 further comprising a server that fetches the metadata for the client.

3. The system of claim 2 wherein the metadata indicates if the second replica is up-to-date.

4. A computer-readable storage medium containing program instructions for synchronizing replicas of a database, the program instructions which when executed by a computer system cause the computer system to execute a method comprising:

sending update data from a first replica to a second replica, the first replica being associated with a first acquire server unit and a first acquire client unit, the second replica being associated with a second acquire server unit and a second acquire client unit;

automatically detecting a failure of the update data from the first replica to be applied to the second replica wherein the detecting comprises;

requesting, by the first acquire client unit from the second acquire server unit, metadata comprising export parameters; and

receiving, by the first acquire client unit from the second acquire server unit, the metadata;

automatically determining a cause of the failure and where the cause of failure occurred, wherein the determining comprises;

determining, by the first acquire client unit, if the failure was due to a packet being lost, wherein the packet contains the update data, wherein the first acquire client unit determines if the failure was due to a packet being lost by requesting from the second acquire server unit, the result of the last failed import to confirm that the packet was actually lost;

parsing, by the first acquire client, the metadata received from the second acquire server unit, wherein the parsed metadata indicates if an account is locked out; and

determining, by the first acquire client unit, if the second replica is updated with current update data;

automatically resolve the cause of the failure, wherein the resolving comprises;

requesting, by the first acquire client unit, for a packet to be resent if the cause of the failure is due to the packet being lost;

resending, by the first acquire client unit, a packet containing the update data if the second replica is not updated with current update data;

unlocking, by the first acquire client unit, an account if the cause of the failure is due to the account being locked out;

deleting, by the first acquire client unit, an object if the cause of the failure is due to the object not being deleted during a previous export;

notifying, by the first acquire client unit, an appropriate authority of the failure if corrective actions need to be taken by the appropriate authority;

resending the update data;

applying the update data to the second replica; and

recording update data in an operations log.