Ok, this is pretty odd but I have found the problem.
Today I have repointed all applications to a different DB server, so I
have been free to do any testing on the problem server.
I started by dropping the databases one by one, dropped em all and the
I stopped crond, even tho Id already looked in crontab and was
satisfied it wasn't the culprit. Problem persisted.
I then removed the mysql data dir, and my.cnf and restarted with a
blank config. Problem still persisted.
Turned on the general log, nothing happening (as nothing legit was
still pointing to the DB on this server). Problem persisted.
Then I thought, what if I have hosts.allow misconfigured and its wide
open maybe a remote system is connecting and messing with it. But
hosts.allow was correct (mysql not listed, so denied by the last
all:all). I tested connecting from a remote server, guess what? Mysql
daemons restarted in exactly the way I was seeing each 7 mins, each
time just by simply running:
mysql -h tau
Odd that, so I added a mysql specific line to the hosts.allow (which
is not necessary as all services are blocked on the last line anyway).
Tested that, no no more crashing. Odd!
The hosts.allow file is the stock FreeBSD updated to not allow all:all
and to use denyhosts (ssh blocked).
Additional info, using tcpdump I could see that the every 7 min
crashes were not in fact caused by any connections from other hosts,
MySQL was crashing regardless.
Still don't know why this would suddenly appear as an issue, or why I
don't see this issue on other identically configured servers... :S