Scalr: The Auto-Scaling Open-Source Amazon EC2 EffortSince EC2 uses Xen as part of their platform this is interesting too:
Scalr is a recently open-sourced framework for managing the massive serving power of Amazon’s Elastic Computing Cloud (EC2) service. While web services have been using EC2 for increased capacity since Fall 2006, it has never been fully “elastic” (scaling requires adding and configuring more machines when the situation arises). What Scalr promises is compelling: a “redundant, self-curing, and self-scaling” network, or a nearly self-sustainable site that could do normal traffic in the morning, and then get Buzz’d in the afternoon.
The Scalr framework is a series of server images, known dully in Amazon-land as Amazon Machine Images (AMI), for each of the basic website needs: an app server, a load balancer, and a database server. These AMIs come pre-built with a management suite that monitors the load and operating status of the various servers on the cloud. Scalr can increase / decrease capacity as demand fluctuates, as well as detecting and rebuilding improperly functioning instances. Scalr is also smart enough to know what type of scaling is necessary, but how well it will scale is still a fair question.
