[Updating only the Analytics list] Hi everybody, I forgot to update this email thread last week. The Event Logging master database switch went fine but as reported the maintenance window affected the Eventlogging schema graphs in the Eventlogging Schema dashboard. For example, this is how the Popups schema looked like: https://grafana.wikimedia.org/dashboard/db/eventlogging-schema?orgId=1&… The gaps are not related to data loss in mysql or data inconsistency, because those are only Kafka throughput metrics. A little refresh about how the events are flowing: Browser --> Varnish cache layer (text/upload) --> Varnishkafka (running on the caching hosts) --> Kafka cluster <---> Eventlogging ---> Mysql databases (Eventlogging Master) I completely stopped the Eventlogging Service while switching the master database and hence its Kafka consumer metrics reflected this, dropping to zero (and spiking up when EL was started back again). The event timestamps are set by Varnishkafka so this action did not affect the final data quality. This maintenance raised a bit of questions in https://phabricator.wikimedia.org/T179914#3764603, apologies for the trouble and the time wasted :( Good news is that the master database was switched without any data loss and we are now using a more powerful host! Thanks! Luca 2017-11-14 18:59 GMT+01:00 Luca Toscano &lt;ltoscano(a)wikimedia.org&gt;rg>: