Aaron Bertrand shares some advice:
Shaving even a handful of seconds from the process can improve the application and end user experience; it can also drastically reduce alert noise or, at least, how long alerts have to stay muted. There’s a lot of material out there about performing AG failovers correctly (no data loss), but far less that focuses on shortening the disruption window. The difference is usually some combination of redo volume, checkpoint behavior, open transactions, and secondary readiness.
I wanted to share some techniques I use to make planned failovers faster and more predictable. Some of these techniques are well documented, while others come from real-world patterns I’ve observed across many SQL Server environments. I’ll talk about what I do before, during, and after the failover to minimize disruption and increase the chance that end users are oblivious that anything happened.
Aaron provides several tips to help reduce the pain of failover.