Starting today, you can proactively rebalance your workloads running on EC2 Spot Instances without having to wait until the Spot Instance receives a two minute Instance interruption notice. You now have access to a new feature called “EC2 Instance rebalance recommendation”, a signal that notifies you when a Spot Instance is at elevated risk of interruption. The signal can arrive sooner than the two minute Spot Instance interruption notice, giving you the opportunity to proactively rebalance your workload to new or existing Spot Instances that are not at elevated risk of interruption. For example, you can start checkpointing your work early to save as much state as possible before the instance is interrupted. Or you can prevent scheduling new work onto the Spot Instances that received the rebalance recommendation, thus increasing the chance of completing the work.
Source:: Amazon AWS