A standby kept in sync that took over the whole platform on the first try, with zero data lost.
A live platform with players online at every hour needed to survive outages, updates and growth without losing data or dropping anyone.
A standby server kept in sync with production, with a tested switchover and switchback, rehearsed with players online: running games keep going and no data is lost. Automatic restore tests of the backups, releases that move players over with nobody disconnected, and measurements that find slowdowns before players do.
When the hosting provider shut down the whole account without warning, the standby took over on the first try with zero data lost. It runs the platform today.