Asterisk logs for 2.1.1

Hi There

I have been running asterisk for the last few years ver 2.1.1. I have a PRI card with over 50 DDIs. Over the past few days the system has been running slow loading hte setup/reports page. Our helpdesk has taken on a new contract and has taken over 500 calls in the last 4 days. The server crashed today and all the phones said no service, I could ping the server but not ssh. In the end I rebooted the server and its working again but I need to find some logs to see what went wrong , i have looked in /var/log but cannot find anything relating to freepbx. Help