I've been seeing these errors intermittently for a while now. Here's an example from the logs:
dovecot: Jul 12 15:59:05 Error: imap-login: Can't connect to auth server at default: Resource temporarily unavailable
The error is EAGAIN. Sometimes it will resolve itself after a few minutes and sometimes it needs to be restarted (it may fix itself, I usually get a phone call if it goes on for very long). I've looked while the problem is occuring and dovecot and dovecot-auth don't have an excessive number of file descriptors open, maybe 10 or 20.
Any ideas or anything else to look at? The system is SuSE Linux 9.2 running kernel 2.6.x. We have seen some odd things happen with these systems, so it is possible that it is not dovecot. The kernel doesn't log anything unusual and other processes seem happy.
Todd