Yesterday, Amazon announced per-second billing for EC2 and EBS. The new calculation will be used starting October 2.
This should allow our community to experiment with new things even more freely, since it removes the minimum of a one-hour charge for a system. If you want to try out an x1.32xlarge system with 128 cores and just under 2 TB of memory, five minutes will cost you $1.112 on October 2 rather than the minimum $13.338 one-hour charge you’d see today.
Also announced yesterday: spot instances can now be stopped and started. It’s now possible to maintain a fleet of persistent spot instances that are started when the spot price drops to your specified levels and are cleanly shut down when it goes back up (rather than being terminated).