Just a heads-up; we're planning to move the backend hosting for Japanese, Korean, Malay, and Thai Wikipedias from our Korean server cluster (yaseo) back to the main servers in Florida (pmtpa) later this week.

They were hosted on the Korean servers for about a year as an experiment in multi-cluster hosting, but in the end we're going to move them back. There are several reasons for this:

* More reliable management.

Experience has shown that software updates and other issues are more likely to have problems on the second cluster, which receives less attention from sysadmins.

These wikis will no longer be second-class citizens where math or timelines sit broken for weeks after a change.

* More efficient use of resources.

As traffic increases, the limited number of servers we have in the yaseo cluster are less able to handle the load. They now frequently overload during peak access hours in Asia, and we can't add new servers as easily as we can in Florida.

Sharing the larger pool of application servers in Florida, and reusing the remaining Korean machines for additional proxy caches, should provide better performance during peak hours in Asia.

* Single-login preparation.

Hosting all the wikis together will let our unified login system work for these wikis along with the others when we finally start it up.

Expected changes and disruptions:

There will be some read-only time for the wikis being moved later this week during the actual transition, but other wikis should not be affected. We will try to do this during off-peak hours in Asia.

URLs for uploaded images will change to use upload.wikimedia.org as on other wikis; old URLs will redirect for compatibility so this should not disrupt anything.

Performance for the moved wikis should be better overall, though off-peak access for logged-in users may be slightly slower due to lightspeed delays between Korea and Florida.

-- brion vibber (brion @ pobox.com)