Surviving a large scale outage requires more than just standing up a few extra servers. Validation and capacity planning can mean the difference between proper mitigation, or just a bunch of wasted effort. This talk will explore how to ensure DR success, gleaned from PagerDuty's production systems. Doug Barth is a Senior Operations Engineer at PagerDuty. He has worked on all parts of the PagerDuty system, but especially moving PagerDuty to a multi-master MySQL cluster, host-to-host transport-layer encryption via IPSec, and recently rebuilding PagerDuty's DR site. Doug developed and operated production systems for Orbitz, a large scale online travel company, and Signal Engage, a startup marketing tool provider in Chicago.