On Thursday 28th July, starting at approx 10pm, we will begin the final stage of a central database server upgrade. We will be upgrading our MySQL servers from v 5.1 to v 5.6, and switching from MyISAM database format to InnoDB. This will give us some speed and reliability advantages. We’ve found a way of doing this with minimal disruption (expecting 2 sub-10 second outages, if that), but this is a core part of our system, and so there is a risk of more significant problems if things don’t go according to plan, along with the possibility of some minor issues elsewhere due to the change in database format.