Hi Kate
Short version:
Some cron-job run by apper filled the disk. It produced about 240GB of data in two files in /tmp - I guess that was also the RAM problem the other day, sind /tmp was in RAM, right?
Anyway, datura killed the processed, deleted the files and commented out the respective jobs in the cron tab. MySQL came back on its own, afaik, but no one knew how to restart replication.
And yes, an admin log is a good idea ;) Oh, and thanks for the great job you are doing for us!
Regards, Daniel