The FileReader restarts excessively. 

In the FileReader logs you see: 

 com.vontu.communication.services.file.sender.RecoveryHandler handleError

Level: INFO: Monitor controller rejected file xxxxxx.xxx. Will back off and retry later.

Level: WARNING
Message:  Exception delivering scan state to scan manager: 
java.lang.OutOfMemoryError: GC overhead limit exceeded

In the BoxMonitor logs for the Detection server you see: 

 com.vontu.communication.transport.ChannelManager processOperationResult

Level: INFO: Operation com.vontu.communication.transport.ReadOperation:1420472408050:filereader:controller-server:null failed with exception: com.vontu.communication.transport.exception.TransportException: remote endpoint closed connection

On the Enforce Server in the MonitorController logs you see: 

 com.vontu.communication.services.file.receiver.FileReceivingHandler newFileShipmentAvailable

Level: WARNING: Rejecting the files from enforce_receiving being received due to overload on folder oce <Detection Server Hostname>:filereader for the sub-system CatalogItemWriterSubsystem. Sender will retry sending the file at a later time.

 com.vontu.communication.dataflow.ReceivingTask run

Level: INFO: Receiving Task(1548): Shipment rejected by application.

In the MonitorController.log: 

Level: INFO   | jvm 3    | 2015/01/03 08:29:35 | Exception in thread "Timer-26" java.lang.OutOfMemoryError: GC overhead limit exceeded

Insufficient java heap size in the SymantecDLPDetectionServer.conf file. 

Increase the heap size in SymantecDLPDetectionServer.conf.

Windows: <Drive>:\Program Files\Symantec\DataLossPrevention\DetectionServer\Services\SymantecDLPDetectionServer.conf
Linux: /opt/Symantec/DataLossPrevention/DetectionServer/Services/SymantecDLPDetectionServer.conf

The default settings are:

# Initial Java Heap Size (in MB)
wrapper.java.initmemory = 128
wrapper.java.maxmemory = 256

Increase the memory 2-4x:

wrapper.java.initmemory = 512
wrapper.java.maxmemory = 1024 

Do not increase the memory beyond 31GB.
At 32GB you lose memory compression and it becomes counter-productive.
 In most circumstances there are better ways to handle out of memory errors than increasing the memory beyond 31GB.