Amazon Elastic Block Store (EBS) enables a single Amazon EC2 instance to attach to one or more highly available, highly reliable storage volumes of up to 1 TB of data each.  Once attached, applications on a single Amazon EC2 instance can read or write from the Amazon EBS volume similar to a disk drive.  With Amazon EBS, an Amazon EC2 instance can now be terminated without losing the data that resides on the Amazon EBS volume.  One use case involves running a relational database within an Amazon EC2 instance, but maintaining the data within an Amazon EBS volume.

For more information, refer to the Amazon Elastic Compute Cloud Developer Guide.

Amazon Elastic Block Store (EBS) provides the ability to take point-in-time snapshots of your data, which are then stored in Amazon S3 for long term durability. Snapshots can also be used to create new Amazon EBS volumes from an existing data set or to restore a volume to an older version. Snapshots are point-in-time consistent and incremental to minimize Amazon S3 costs. This means that a snapshot will only contain the data in your volume that has changed since your last snapshot. Previous snapshots of your volume will continue to be available until they are deleted.

For more information, refer to the Amazon Elastic Compute Cloud Developer Guide.

There is a 20 volume per account limit during the beta. If you need more than 20 volumes, go to http://www.amazon.com/gp/html-forms-controller/ebs_volume_limit_request.

The instance-type is only available as part of the instance metadata on instances that expose version 2007-09-28 of the instance metadata. Large and extra large instance types support this version. Small instances types (the original instance type) may not support this version yet, in which case the instance type of m1.small can be assumed. You can query supported versions using the following URL: http://169.254.169.254/.