Southwards Datacentre Switchover (September 2026)

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Hello all,

On Wednesday September 23rd 2026, the SRE team will run a planned
datacenter switchover, moving all wikis from eqiad to codfw. 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 eqiad that normally run 24 hours a
day.

The switchover process requires a brief read-only period for all
Foundation-hosted wikis, which will start on Wednesday September 23rd 2026
@ 14:00 UTC, and will last for just 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 editing will be
unavailable 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.

MoveComms 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. To report any issues, you can reach
us in #wikimedia-sre on IRC, or file a Phabricator ticket with the
#datacenter-switchover tag (
https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?projects=Datacenter-Switchover;
we'll be monitoring closely for reports of trouble during and after the
switchover. The switchover and its preparation will be tracked under
https://phabricator.wikimedia.org/T433363.

On behalf of the SRE team, please excuse the disruption, and we would like
to thank everyone in various departments who are involved in planning this
work. If you have any questions, please reply directly to this email.

Kind Regards,

-- 
Simon Lyngshede
Site Reliability Engineer / Traffic
Wikimedia Foundation

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<div dir=3D"ltr"><div><div>Hello all,<br><br>On Wednesday September 23rd 20=
26, the SRE team=20
will run a planned datacenter switchover, moving all wikis from eqiad to
 codfw. This is an important periodic test of our tools and procedures,=20
to ensure the wikis will continue to be available even in the event of=20
major technical issues in our primary home. It also gives all our SRE=20
and ops teams a chance to do maintenance and upgrades on systems in=20
eqiad that normally run 24 hours a day.<br><br>The switchover process=20
requires a brief read-only period for all Foundation-hosted wikis, which
 will start on Wednesday September 23rd 2026 @ 14:00 UTC, and will last=20
for just a few minutes while we execute the migration as efficiently as=20
possible. All our public and private wikis will be continuously=20
available for reading, as usual, but editing will be unavailable during=20
the process. Users will see a notification of the upcoming maintenance,=20
and anyone still editing will be asked to try again in a few minutes. =C2=
=A0<br><br>MoveComms will soon begin notifying communities of the read-only=
 window.<br><br>If
 you like, you can follow along on the day in the public=20
#wikimedia-operations channel on IRC. To report any issues, you can=20
reach us in #wikimedia-sre on IRC, or file a Phabricator ticket with the
 #datacenter-switchover tag (<a href=3D"https://phabricator.wikimedia.org/m=
aniphest/task/edit/form/1/?projects=3DDatacenter-Switchover" target=3D"_bla=
nk">https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?projects=
=3DDatacenter-Switchover</a>;
 we&#39;ll be monitoring closely for reports of trouble during and after th=
e
 switchover. The switchover and its preparation will be tracked under <a hr=
ef=3D"https://phabricator.wikimedia.org/T433363" target=3D"_blank">https://=
phabricator.wikimedia.org/T433363</a>.<br><br>On
 behalf of the SRE team, please excuse the disruption, and we would like
 to thank everyone in various departments who are involved in planning=20
this work. If you have any questions, please reply directly to this=20
email.<br><br>Kind Regards,</div><font color=3D"#888888"></font></div><br><=
span class=3D"gmail_signature_prefix">-- </span><br><div dir=3D"ltr" class=
=3D"gmail_signature" data-smartmail=3D"gmail_signature"><div dir=3D"ltr"><d=
iv>Simon Lyngshede</div><div><div style=3D"color:rgb(0,0,0);font-family:Hel=
vetica;font-size:12px;font-style:normal;font-weight:400;letter-spacing:norm=
al;text-align:start;text-indent:0px;text-transform:none;white-space:normal;=
word-spacing:0px;text-decoration:none"></div><div style=3D"color:rgb(0,0,0)=
;font-family:Helvetica;font-size:12px;font-style:normal;font-weight:400;let=
ter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;whi=
te-space:normal;word-spacing:0px;text-decoration:none">Site Reliability Eng=
ineer / Traffic=C2=A0</div><div style=3D"color:rgb(0,0,0);font-family:Helve=
tica;font-size:12px;font-style:normal;font-weight:400;letter-spacing:normal=
;text-align:start;text-indent:0px;text-transform:none;white-space:normal;wo=
rd-spacing:0px;text-decoration:none"><div>Wikimedia Foundation</div></div><=
br><br></div></div></div></div>

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