Apparently the site was down while I slept, but I had emails & comments in my inbox about the outage as soon as I got up so I was able to jump on it right away.
The Squid had run out of memory again. The access log files for one day were 17 gigs. That seems awfully high – maybe we’re getting spidered too hard or the logs go through serious stress after a restart?
I’ll be finding a more permanent solution to the issue, but in the meantime the site is “up” but it’s going to be fairly slow while the cache refills… again.