labsdb1001.eqiad.wmnet (aka c1.labsdb) will be rebooted at 2017-10-30 14:30 UTC for kernel updates (https://phabricator.wikimedia.org/T168584).
Normal usage of the *.labsdb databases should experience only limited interruption as DNS is changed to point to the labsdb1003.eqiad.wmnet (aka c3.labsdb). The c1.labsdb service name will *not* be updated however, so tools hardcoded to that service name will be interrupted until the reboot is complete.
There is a possibility of catastrophic hardware failure in this reboot. There will be no way to recover the server or the data it currently hosts if that happens. Tools that are hosting self-created data on c1.labsdb *will* lose that data if there is hardware failure. If you are unsure if your tool is hosting data on c1.labsdb, you can check at https://tools.wmflabs.org/tool-db-usage/.
This reboot is an intermediate step before the complete shutdown of the server on Wednesday 2017-12-13. See https://wikitech.wikimedia.org/wiki/Wiki_Replica_c1_and_c3_shutdown for more information.
Bryan (on behalf of the Wikimedia Cloud Services and DBA teams)