HTTP 500 error Hard Drive Full

It appears that the file has filled up my 30g harddrive. Is there a way for me to put a limitation on this file size? The flow_log_1.txt file is currently at 27g.

Thanks!

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
java.util.Hashtable.put(Unknown Source)
com.adventnet.netflow.beans.ReportDetailsBean.getGraphPageResults(ReportDetailsBean.java:126)
org.apache.jsp.jspui.traffic_jsp._jspService(traffic_jsp.java:462)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
com.adventnet.netflow.utils.EncodingFilter.doFilter(EncodingFilter.java:45)

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.