Due to an unexpected production database outage during last week's maintenance window, we were unable to complete the Beta Cluster database migration to the new Debian jessie instances. We'll be performing this migration during a three-hour read-only maintenance window tomorrow from 1400-1700 UTC.
Please contact Release Engineering (#wikimedia-releng) if you have concerns/questions regarding this process, or refer to the Phabricator task (T138778).
https://phabricator.wikimedia.org/T138778
Thanks, Dan