The ethernet controller on the server that provides /home pages wedged today. Most services depend upon being able to access /home and were unavailable as a result.
As near as I can tell looking at the logs, the ethernet wedged shortly after 5AM but I did not receive any telephone calls until around 11AM. I was unable to fix it from here so I had to drive to the co-location facility.
Everything was back in service at 12:46 (afternoon).