When using CloudFormation or the Amazon CLI, please use the following JSON to specify volume sizes and encryption options on your new EC2 instance:
"ec2-instance": {
    "Type": "AWS::EC2::Instance",
    "Properties": {
      "ImageId": "ami-xxxxxxxxx",
      "InstanceType": "t2.small",
      "KeyName": "my-ec2-keypair",
      "BlockDeviceMappings": [
        { "DeviceName": "/dev/sda1",
         "Ebs": {
                "DeleteOnTermination":"true",
               "VolumeType":"gp2",
                "VolumeSize":"100"
         }
     },
       { "DeviceName": "/dev/xvdl",
       "Ebs": {
                "DeleteOnTermination":"true",
                  "VolumeType":"gp2",
                "VolumeSize":"10"
          }
     },
       { "DeviceName": "/dev/xvdh",
       "Ebs": {
                "DeleteOnTermination":"true",
                  "VolumeType":"gp2",
                "VolumeSize":"2"
       }
     },
       { "DeviceName": "/dev/xvdx",
       "Ebs": {
                  "DeleteOnTermination":"true",
                    "VolumeType":"gp2",
                  "VolumeSize":"2"
       }
     },
     ]
 }
}
If you are creating EC2 instances from the Amazon console, override the default volume sizes on Page 4 of the Launch Instance wizard.

(If you prefer an EC2 instance with a single root volume, please e-mail [email protected] and let us know. We're happy to accommodate!)