All Wikimedia sites will be unavailable for about 30 minutes between 04:00 and 08:00 UTC while we switch master database server.

Why the switch? Even with compression, the disk space free for logs and temporary files on the current master, Ariel, is now down to 15GB. About 100GB will become available after compression but that can't be made free while Ariel is master. So, we're switching back to Suda, the master we used for the first half of 2004. That now has larger disks and about 120GB of free space. Meanwhile, MediaWiki 1.4 has been released and that shifts much of the database load from the master to the slaves, so the master now sees about 650 relatively easy queries per second instead of 3,000 queries, many of which are problematic. Suda has been shown to be fine up to 1,400 of those mixed problematic queries and should do better still on the remaining master-only queries. So: no need to accept the risk of running out of space on Ariel and we'll get plenty of free space back on it later. Ultimately Ariel is destined to become a slave on the en+ja part of a split set of master/slave servers, each set handling half of the site load. Estimated time for that split is about April 2005, adjusted based on load and growth rates.

Updates on when the switch starts and completes will, as usual, be at Wikipedia Status on OpenFacts:

http://openfacts.berlios.de/index-en.phtml?title=Wikipedia_Status