Amazon’s Elastic Compute Cloud isn’t abstract – it’s real and impressive. EC2 enables any developer to leverage Amazon’s own benefits of massive scale with no up-front investment or performance compromises. Being elastic it instantly responds unexpectedly changing computing requirements. EC2 security groups make it very simple to partition your application environment at no additional cost. With EC2 security groups, you can completely isolate every tier, even internally to the cloud. Based on Xen EC2 security relies on VM isolation. There is still a possibility that Xen has security holes that would allow inter-VM communication.

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