Predicting validity of data replication prior to actual replication in a transaction processing system
A method, computer program product and computer system to validate a write of a replica record to a replica data store in a transaction processing system, the replica record duplicating a source record in a source data store. The transaction processing system obtains a value associated with a record location of the source record in the source data store. The transaction processing system predicts a value associated with a record location of the replica record in the replica data store and responsive to the obtained value associated with the source record location not corresponding to the predicted value associated with the replica record location, not writing the replica record.
1. A method for validating a write of a replica record to a replica data store in a transaction processing system, the replica record duplicating a source record in a source data store, the method comprising:
writing, by the transaction processing system, the source record to a location in the source data store;
obtaining, by the transaction processing system, the location of the source record in the source data store;
predicting, by the transaction processing system, the location in the replica data store to which the replica record will be written, based on the location and length of the previous replica record;
responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record:
not writing the replica record;
signaling, to the transaction processing system, a replica record location prediction failure; and
ending replication;
responsive to determining that the obtained location of the source record corresponds to the predicted location of the replica record location, writing, by the transaction processing system, the replica record to a location in the replica data store; and
responsive to determining that the obtained location of the source record does not correspond to the location in the replica data store to which the replica record was written, identifying the replica data store as corrupted.
2. The method according to claim 1 , wherein the source data store and the replica data store are Virtual Storage Access Method (VSAM) Entry Sequenced Data Sets (ESDS).
3. The method according to claim 1 , wherein each of the obtained location of the source record location, the predicted location of the replica record location, and the actual location to which the replica record will be written is a relative byte address (RBA).
4. The method according to claim 1 , wherein the transaction processing system is a Customer Information Control System (CICS).
5. The method according to claim 2 , wherein responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record comprises:
predicting, by the transaction processing system, a second location in a next control interval in the replica data store; and
responsive to determining that the obtained location of the source record location does not correspond to the second predicted location:
not writing the replica record;
signaling, to the transaction processing system, a replica record location prediction failure; and
ending replication.
6. A computer program product for validating a write of a replica record to a replica data store in a transaction processing system, the replica record duplicating a source record in a source data store, the computer program product comprising one or more computer-readable tangible non-transitory storage devices and program instructions stored on at least one of the one or more computer-readable tangible non-transitory storage devices, the program instructions comprising:
program instructions to write, by the transaction processing system, the source record to a location in the source data store;
program instructions to obtain, by the transaction processing system, the location of the source record in the source data store;
program instruction to predict, by the transaction processing system, the location in the replica data store to which the replica record will be written, based on the location and length of the previous replica record; and
responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record, program instructions to:
not write the replica record;
signal, to the transaction processing system, a replica record location prediction failure; and
end replication;
responsive to determining that the obtained location of the source record corresponds to the predicted location of the replica record location, program instructions to write, by the transaction processing system, the replica record to a location in the replica data store; and
responsive to determining that the obtained location of the source record does not correspond to the location in the replica data store to which the replica record was written, program instructions to identify the replica data store as corrupted.
7. The computer program product according to claim 6 , wherein each of the obtained location of the source record location, the predicted location of the replica record location, and the actual location to which the replica record will be written is a relative byte address (RBA).
8. The computer program product according to claim 6 , wherein the transaction processing system is a Customer Information Control System (CICS).
9. The computer program product according to claim 6 , wherein the source data store and the replica data store are Virtual Storage Access Method (VSAM) Entry Sequenced Data Sets (ESDS).
10. A computer system for validating a write of a replica record to a replica data store in a transaction processing system, the replica record duplicating a source record in a source data store, the computer system comprising one or more processors, one or more computer readable memories, one or more computer readable tangible storage devices, and program instructions stored on at least one of the one or more storage devices for execution by at least one of the one or more processors via at least one of the one or more memories, the program instructions comprising:
program instructions to write, by the transaction processing system, the source record to a location in the source data store;
program instructions to obtain, by the transaction processing system, the location of the source record in the source data store;
program instruction to predict, by the transaction processing system, the location in the replica data store to which the replica record will be written, based on the location and length of the previous replica record; and
responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record, program instructions to:
not write the replica record;
signal, to the transaction processing system, a replica record location prediction failure; and
end replication;
responsive to determining that the obtained location of the source record corresponds to the predicted location of the replica record location, program instructions to write, by the transaction processing system, the replica record to a location in the replica data store; and
responsive to determining that the obtained location of the source record does not correspond to the location in the replica data store to which the replica record was written, program instructions to identify the replica data store as corrupted.
11. The computer system according to claim 10 , wherein each of the obtained location of the source record location, the predicted location of the replica record location, and the actual location to which the replica record will be written is a relative byte address (RBA).
12. The computer program product according to claim 9 , wherein responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record comprises program instructions to:
predict, by the transaction processing system, a second location in a next control interval in the replica data store; and
responsive to determining that the obtained location of the source record location does not correspond to the second predicted location:
not writing the replica record;
signaling, to the transaction processing system, a replica record location prediction failure; and
ending replication.
13. The computer system according to claim 10 , wherein the source data store and the replica data store are Virtual Storage Access Method (VSAM) Entry Sequenced Data Sets (ESDS).
14. The computer system according to claim 13 , wherein responsive to determining that the obtained location of the source record does not correspond to the predicted location of the replica record comprises program instructions to:
predict, by the transaction processing system, a second location in a next control interval in the replica data store; and
responsive to determining that the obtained location of the source record location does not correspond to the second predicted location:
not writing the replica record;
signaling, to the transaction processing system, a replica record location prediction failure; and
ending replication.