Defined in github.com/aws/aws-sdk-go/service/ec2/api.go
The virtual device name (ephemeralN). Instance store volumes are numbered starting from 0. An instance type with 2 available instance store volumes can specify mappings for ephemeral0 and ephemeral1.The number of available instance store volumes depends on the instance type. After you connect to the instance, you must mount the volume.
Constraints: For M3 instances, you must specify instance store volumes in the block device mapping for the instance. When you launch an M3 instance, we ignore any instance store volumes specified in the block device mapping for the AMI.