You might want to upgrade to 12.1RU5 instead. The release notes say this has been resolved:
http://www.symantec.com/docs/TECH224706
Data truncation errors and AVman log build up on Symantec Endpoint Protection Manager
Fix ID: 3277833
Symptom: Error log files (.err) build-up in the AVMan directory. The scm-server-0.log shows the following error message:
<computercode style="font-family: 'Courier New'; font-size: 12pt; color: rgb(34, 34, 34); line-height: 20px;">SEVERE: Datastore error in: com.sygate.scm.server.task.AgentAVLogCollector java.sql.DataTruncation: Data truncation</computercode>
This may result in a performance degradation of the manager and inability to log on to the console or perform other tasks.
Solution: Truncate URL data before insertion into the database. This resolves a scenario where the length of the URL data is longer than the column length.