Spot Pricing in IaaS Clouds

Amazon’s introduction of spot pricing for EC2 servers a few weeks back was a sign that cloud service providers need to find ways to improve the utilization of their infrastructure if they are to make public cloud services attractive for a wider range of applications and for large enterprises that enjoy good economies of scale in their own data centers. Spot instances are clearly an attractive way for the service provider to sell off temporarily unused capacity at the best possible price, but can only be used for running background jobs that do not have to complete by a certain time. Many enterprises no doubt have such jobs, but the challenge with the spot pricing model as introduced by Amazon is that the spot instances are taken away without notice if the spot price exceeds the customer’s maximum price. This limits their use to either short running jobs or jobs that run applications that can gracefully recover from a server failure. I wonder why there isn’t an option to snap a spot instance to permanent storage before it is terminated; after all these are just XEN virtual machines. In any case, until such capability becomes available, cloud users interested in using spot instances for long-running jobs could check out our AvS Checkpoint/Restart product. More in general, if you’re using a public Infrastructure Cloud and have concerns about the reliability of the service for long-running background jobs, a Checkpoint/Restart facility could broaden the range of applications you can run in the cloud.