I found yesterday that a customer’s SOLR server was almost out of disk space (<50MB free on C), so I investigated the issue. I found that by default, every visitor is being logged to a file that rolls over every day. In the production environment, this turned into over 4GB of logs per day. The setting that controls this is in the following location:
C:\Program Files\Apache Software Foundation\Tomcat 7.0\conf\server.xml
and the node that controls the log is this one:
<Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
pattern="%h %l %u %t "%r" %s %b" resolveHosts="false"/>
In the case of our sites, the ASP.Net instance (us) calls out to SOLR to perform searches and we crunch the results server-side. That being the case, we have no need to log our own traffic; commenting out this node turns off the logging of visitors, thus alleviating the issue.