WARNING Retrying Bulk Insert for file:sqlldr due to Communication Error:256

I am running my engine on Linux and am receiving an intermittent message

"WARNING Retrying bulk insert for file: sqlldr due to communication Error: 256"

The engine seems to have completed successfully, but it is not clear if this error caused some of the forecast to not complete. It is also not clear what caused the error.

Generally if you see only the WARNING of it, it means that next retries of the same load request have eventually succeeded and so the run a a whole is not affected.

In order to know more about what happens, look for .log/.bad files left in the engines bin directory or possibly a quote of them within the specific engine log that had the issue.  The sqlnet.log file may also have some information about it and perhaps at the database server side there may be some log/alert regarding what happened.  Look at the alert.log.

In general it could be that the database server/network was over loaded at the time and somehow the connection was rejected/failed/aborted either due to specific setting on concurrent connections/sessions or inadvertently due to glitch in network/os/hardware.

If this repeats and becomes more frequent during the run you should look further into it as mentioned above.

You can also track this using either SQL*Trace or java.util.logging. 

- Globally enable logging by setting the oracle.jdbc.Trace system property java -Doracle.jdbc.Trace=true

- Client Side Tracing:

Your SQLNET.ORA file should contain the following lines to produce a client side trace file:

trace_level_client = 10
trace_unique_client = on
trace_file_client = sqlnet.trc
trace_directory_client = <path_to_trace_dir>

Server Side Tracing:

To enable server side tracing, use the following parameters:

trace_level_server = 10
trace_file_server = server.trc
trace_directory_server = <path_to_trace_dir>

Tracing Levels:

The following values can be used for TRACE_LEVEL* parameters:

    16 or SUPPORT — WorldWide Customer Support trace information
    10 or ADMIN — Administration trace information
    4 or USER — User trace information
    0 or OFF — no tracing, the default

Additional information is readily available via the web.