Amazon Machine Image
An Amazon Machine Image (AMI) is a special type of virtual appliance that is used to create a virtual machine within the Amazon Elastic Compute Cloud ("EC2"). It serves as the basic unit of deployment for services delivered using EC2. Overview Like all virtual appliances, the main component of an AMI is a read-only filesystem image that includes an operating system (e.g., Linux, Unix, or Windows) and any additional software required to deliver a service or a portion of it. An AMI includes the following: A template for the root volume for the instance (for example, an operating system, an application server, and applications) Launch permissions that control which AWS accounts can use the AMI to launch instances A block device mapping that specifies the volumes to attach to the instance when it's launched The AMI filesystem is compressed, encrypted, signed, split into a series of 10 MB chunks and uploaded into Amazon S3 for storage. An XML manifest file stores information about the AMI, including name, version, architecture, default kernel id, decryption key and digests for all of the filesystem chunks. Current AMIs are available for hardware virtualized machines (HVM) where the operating system is installed as it would