Dear Wikitechians,

On *Wednesday September 20th*, the SRE team will run a planned data center switchover, moving all wikis from our data center in Virginia to the data center in Texas. This is an important periodic test of our tools and procedures, to ensure the wikis will continue to be available even in the event of major technical issues in our primary home. It also gives all our SRE and ops teams a chance to do maintenance and upgrades on systems in Virginia that normally run 24 hours a day.

The switchover process requires a *brief read-only period for all Foundation-hosted wikis*, which will start at *14:00 UTC on Wednesday **September 20th*, and will last for a few minutes while we execute the migration as efficiently as possible. All our public and private wikis will be continuously available for reading as usual, but no one will be able to save edits during the process. Users will see a notification of the upcoming maintenance, and anyone still editing will be asked to try again in a few minutes.

CommRel will soon begin notifying communities of the read-only window.

If you like, you can follow along on the day in the public #wikimedia-operations channel on IRC (instructions for joining here https://meta.wikimedia.org/wiki/IRC/Instructions). To report any issues, you can reach us in #wikimedia-sre on IRC, or file a Phabricator ticket with the *datacenter-switchover* tag (pre-filled form here https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?projects=Datacenter-Switchover&subscribers=kamila); we'll be monitoring closely for reports of trouble during and after the switchover. (If you're new to Phab, there's more information at Phabricator/Help.) The switchover and its preparation will be tracked in Phabricator task T345263 https://phabricator.wikimedia.org/T345263.

On behalf of the SRE team, please excuse the disruption, and our thanks to everyone in a number of departments who've been involved in planning this work. Feel free to reply directly to me with any questions.

Thank you,

Kamila Součková (they/them) Senior SRE Wikimedia Foundation