Transaction completion during cluster failover

You can configure servers in a high-availability cluster environment to continue processing transactions after failover of the primary server.

Transactions running on any server except the failed primary server continue to run. Configure the cluster environment for the following results:
  • Transactions running on secondary servers are not affected.
  • Transactions running on the secondary server that becomes the primary server are not affected.
  • Transactions running on the failed primary server are terminated.

Transaction completion after failover is not supported for smart large objects, XA transactions, and when running DDL statements on secondary servers.

When a failover occurs, the secondary servers in the cluster temporarily suspend running user transactions until the new primary server is running. After failover, the secondary servers resend the saved transactions to the new primary server. The new primary server resumes execution of the transactions from the surviving secondary servers.

When distributed transactions (transactions that span multiple database servers) are running, any transaction that is running on the primary server at the time of server failure is terminated.

When failover occurs, whether it is manual or performed by the Connection Manager, the database server that receives failover must have the most advanced log-replay position of all active servers in the cluster. If the database server that receives failover does not have the most advanced log replay position, all transactions in the cluster are terminated and rolled back. Because the primary and SD secondary server read from the same physical disk, failover to an SD secondary server should occur first. If the failover server is an HDR secondary server, SD secondary servers are shut down.

For best Connection Manager failover performance, use the FOC ORDER=ENABLED setting in the Connection Manager configuration file, and set the HA_FOC_ORDER configuration parameter on the cluster's primary server.


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