Hi,
I will be migrating wm-bot's database server to new box running postgres today. It shouldn't harm any log collection in channels where logging is enabled, but it will make it impossible to use the SQL based viewer at http://tools.wmflabs.org/wm-bot/logs for a while (I hope just few hours).
The reason for the outage is that migration will take 2 parts: First I replace bot core with version that uses postgres - that shouldn't take more than 1 second. Since that moment new logs will be written to postgres, but old would still stay in MySQL. Then I will have to move all data to postgres, logs table has millions of rows and about 8GB so that might take a while...
So, there should be no outage in logs but web viewer won't be working for a while.
The reason for migration is that MySQL doesn't scale very well, is missing lots of useful features (roles, tablespaces and lots of other advanced stuff that is very useful on labs - it supports nfs based storage and so on), and the old server basically ran out of space.