Singleton adapters issues in HA

Recently I  faced with the issue of Singleton (non-concurrent) adapters in HA (clustered environment). Two instances were created for a single file that resulted in a file will be processed twice.

Singleton adapters can not run in active-active configuration. For this type of adapters you must make sure there is only one adapter instance active at runtime independent of the number of clusters you have. This effectively means you will only have one non-concurrent adapter at runtime. If this active adapter fails, one of the passive adapter becomes active.

There are a lot resources in metalink that you will be able to use. I have listed some of them below.

How to Enable a Singleton Adapter in an ESB Cluster Environment

How to Enable a Singleton Adapter in BPEL Cluster Environment

How to Setup FileAdapter in Cluster for High Availability
and more can be found on metalink.