Downtime
As with every system, sometimes services or servers need a reboot or some other love which makes them not available for the rest of the world.
The Services Team tries together with the Boosters Team to keep such downtimes as short as possible. Most of the time, we try to keep the visible downtime to zero - so nobody should notice it. But sometimes we need more time - if that's the case, we inform our community via http://news.opensuse.org/. If needed, we try to post the exact reason here in the wiki.