Data replication across servers

Abstract

Embodiments of the present invention provide methods, systems, and computer program products for replicating data between redundant sources. In one embodiment, during a reverse replication process, roles of a source system and target system are altered such that the target system controls the replication process. The target system can identify objects to be transferred, build batches of objects for efficient transfer, and transmit the batches of objects to the source system. Accordingly, embodiments of the present invention can reduce inefficient communication between a source system and a target system that might otherwise occur during replication processes controlled by the source system.

What is claimed is: 
     
         1 . A method for replicating data between redundant resources, the method comprising:
 receiving, at a source computer system, an instruction to replicate the source computer system and a target computer system;   identifying, by one or more computer processors, one or more objects stored in the target computer system that are not stored in the source computer system;   transmitting, by one or more computer processors, a request from the source computer system to the target computer system for the one or more identified objects;   generating, at the target computer, one or more batches of objects comprising the one or more identified objects; and   transmitting the one or more batches of objects from the target computer system to the source computer system.   
     
     
         2 . The method of  claim 1 , further comprising:
 responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmitting an instruction from the source computer system to the target computer system to build the one or more batches of objects.   
     
     
         3 . The method of  claim 1 , wherein identifying the one or more objects stored in the target computer system that are not stored in the source computer system comprises:
 determining, by one or more computer processors, that the source computer system is unavailable for a period of time; and   generating, by one or more computer processors, a list of one or more objects in the target system that are created, modified, or deleted during the period of time for which the source computer system is unavailable.   
     
     
         4 . The method of  claim 1 , wherein identifying the one or more objects stored in the target computer system that are not stored in the source computer system comprises:
 comparing, by one or more computer processors, a first list of objects on the source computer system with a second list of objects on the target computer system to identify one or more objects in the second list of objects that are not in the first list of objects.   
     
     
         5 . The method of  claim 1 , further comprising:
 responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmitting, from the source computer system to the target computer system, an instruction to initiate a replication operation.   
     
     
         6 . The method of  claim 1 , wherein the request from the source computer system to the target computer system for the one or more identified objects comprises a request in a structured query language. 
     
     
         7 . The method of  claim 1 , wherein the source computer system receives the instruction to replicate the source computer system and the target computer system in response to detecting that one or more objects stored in the source computer system have been modified since a previous replication. 
     
     
         8 . A computer program product for replicating data between redundant resources, the computer program product comprising:
 one or more computer-readable storage media and program instructions stored on the one or more computer-readable storage media, the program instructions comprising:
 program instructions to receive, at a source computer system, an instruction to replicate the source computer system and a target computer system; 
 program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system; 
 program instructions to transmit a request from the source computer system to the target computer system for the one or more identified objects; 
 program instructions to generate, at the target computer, one or more batches of objects comprising the one or more identified objects; and 
 program instructions to transmit the one or more batches of objects from the target computer system to the source computer system. 
   
     
     
         9 . The computer program product of  claim 8 , wherein the program instructions stored on the one or more computer-readable storage media further comprise:
 program instructions to, responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmit an instruction from the source computer system to the target computer system to build the one or more batches of objects.   
     
     
         10 . The computer program product of  claim 8 , wherein the program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system comprise:
 program instructions to determine that the source computer system is unavailable for a period of time; and   program instructions to generate a list of one or more objects in the target system that are created, modified, or deleted during the period of time for which the source computer system is unavailable.   
     
     
         11 . The computer program product of  claim 8 , wherein the program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system comprise:
 program instructions to compare a first list of objects on the source computer system with a second list of objects on the target computer system to identify one or more objects in the second list of objects that are not in the first list of objects.   
     
     
         12 . The computer program product of  claim 8 , wherein the program instructions stored on the one or more computer-readable storage media further comprise:
 program instructions to, responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmit, from the source computer system to the target computer system, an instruction to initiate a replication operation.   
     
     
         13 . The computer program product of  claim 8 , wherein the request from the source computer system to the target computer system for the one or more identified objects comprises a request in a structured query language. 
     
     
         14 . The computer program product of  claim 8 , wherein the source computer system receives the instruction to replicate the source computer system and the target computer system in response to detecting that one or more objects stored in the source computer system have been modified since a previous replication. 
     
     
         15 . A computer system for replicating data between redundant resources, the computer system comprising:
 one or more computer processors;   one or more computer-readable storage media;   program instructions stored on the computer-readable storage media for execution by at least one of the one or more processors, the program instructions comprising:
 program instructions to receive, at a source computer system, an instruction to replicate the source computer system and a target computer system; 
 program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system; 
 program instructions to transmit a request from the source computer system to the target computer system for the one or more identified objects; 
 program instructions to generate, at the target computer, one or more batches of objects comprising the one or more identified objects; and 
 program instructions to transmit the one or more batches of objects from the target computer system to the source computer system. 
   
     
     
         16 . The computer system of  claim 15 , wherein the program instructions stored on the computer-readable storage media further comprise:
 program instructions to, responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmit an instruction from the source computer system to the target computer system to build the one or more batches of objects.   
     
     
         17 . The computer system of  claim 15 , wherein the program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system comprise:
 program instructions to determine that the source computer system is unavailable for a period of time; and   program instructions to generate a list of one or more objects in the target system that are created, modified, or deleted during the period of time for which the source computer system is unavailable.   
     
     
         18 . The computer system of  claim 15 , wherein the program instructions to identify one or more objects stored in the target computer system that are not stored in the source computer system comprise:
 program instructions to compare a first list of objects on the source computer system with a second list of objects on the target computer system to identify one or more objects in the second list of objects that are not in the first list of objects.   
     
     
         19 . The computer system of  claim 15 , wherein the program instructions stored on the computer-readable storage media further comprise:
 program instructions to, responsive to transmitting the request from the source computer system to the target computer system for the one or more identified objects, transmit, from the source computer system to the target computer system, an instruction to initiate a replication operation.   
     
     
         20 . The computer system of  claim 15 , wherein the source computer system receives the instruction to replicate the source computer system and the target computer system in response to detecting that one or more objects stored in the source computer system have been modified since a previous replication.