Quote Originally Posted by Adeacia View Post
This.^ The worlds in a data center are all connected to each other and share the same instance servers. Data centers themselves are completely separate from each other.

This is by design to make it easier to manage the worlds and instances. Like having less people all trying to use the same instance servers at the same time, which as the start of SB showed there were still too many people at once.

Splitting up worlds to make a new data center is the best option in this case to help prevent that from happening again, or at least mitigate it.
To be fair, the instance clogged occurred primarily because they foolish stuck one ten quests into the MSQ. This meant the usual drop-off which would occur as players each progress at various speeds never happened. This problem was only magnified by making an instance for both Red Mage and Samurai in their opening job quest.