Backup system that's partially running and can take over quickly but not instantly. Like having a car engine that's warmed up but not fully running.
E-commerce sites use warm standby systems that can activate within minutes, balancing cost and recovery speed.
Warm standby is a disaster recovery (DR) pattern, not a single managed service. On all major clouds, it’s typically implemented by running a smaller-capacity copy of your production stack (compute, databases, networking) in a secondary region/zone, keeping data replicated, and scaling up plus switching traffic during a failover.