The secondary database server we use for +fav recommendation queries stopped responding for a while (possibly processing backed-up writes, it's only got hard disks, albeit six of them). These queries fell back to the primary server, but it wasn't able to cope with them and do everything else - which is why we put it on a secondary server in the first place. We've shifted the traffic back and it's working now. Sorry for the inconvenience!
The secondary database server we use for +fav recommendation queries stopped responding for a while
