I have rented a Centos6 server and running an Apache Tomcat 7 server with an Apache httpd server proxying it.

Sometimes my server gets locked and I cannot access it via putty even ping.

My question is: how can I be sure that this is about connection problems or application servers (I currently have a hibernate problem that causes the app servers not to respond because of unneeded heavy queries)?

Thanks in advance.

(PS: Fixing the problem by restarting the server)

EDIT: Following are the applications and props on my server:

\*Apache httpd server --> proxy,
\*Apache Tomcat server --> app server,
\*Mysql DBMS

And got hd images appr. 69000 (99GB) serving from one folder.

EDIT2: The system comes back normal when I restart machine and run the servers again.