My comments are based on an answer about dovecot generating ssl parameters.
The file /var/lib/dovecot/ssl-parameters.ssl (ssl-parameters.dat on CentOS 6) mentioned in the other answer is regenerated weekly. In my logs, this process takes from 5 sec to over a min. Overnight, my logs had these messages:
Dec 12 17:34:14 xxxx dovecot: ssl-params: Generating SSL parameters
Dec 12 17:34:23 xxxx dovecot: ssl-params: SSL parameters regeneration completed
Dec 12 17:34:24 xxxx dovecot: ssl-params: Error: epoll_ctl(del, 7) failed: No such file or directory
This morning, the time stamp on ssl-parameters.dat is 2015-12-12 17:34:23.
I think that:
- regenerating the SSL parameters file is independent of whatever is checking for its existence
- this error occurs when the SSL parameters file is accessed (for whatever reason) while it is being regenerated
- although my error was logged after the regeneration completed, it likely occurred during the window when the file did not exist
This may represent a bug in dovecot. Perhaps this file could be replaced atomically or a locking mechanism added. That said, this error does not seem to manifest other than in the log.