blockDeviceMappings
The block device mappings.
When using the CreateImage action:
You can't change the volume size using the VolumeSize parameter. If you want a different volume size, you must first change the volume size of the source instance.
You can't modify the encryption status of existing volumes or snapshots. To create an AMI with volumes or snapshots that have a different encryption status (for example, where the source volume and snapshots are unencrypted, and you want to create an AMI with encrypted volumes or snapshots), use the CopyImage action.
The only option that can be changed for existing mappings or snapshots is
DeleteOnTermination
.