Below are a collection of links that can be used to try to monitor the health of the Tier 3 components. If you see unexpected behavior--fewer than normal running jobs, slower job I/O, failing file transfers, etc.--please check here for indications of what might be wrong.
Note: Unless otherwise noted, the links below only work for those on campus or connected with a VPN.
Worker nodes: http://mon.crc.nd.edu/xymon/d6copt/condor/condor.html
Network Testing to Multiple Sites