I have the same problem like this:

https://www-secure.symantec.com/connect/forums/sepmdatainboxlogtexavman-dat-files-not-clearing

This is SEPM 12.1 with embedded database. The err files are non-stop generating. How can i stop it?

I suggest you can raised support ticket.

See this articles if help

Symantec Endpoint Protection Manager does not parse client forwarded logs in a timely manner.

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.