By default the ‘DeleteOnTermination’ attribute of an EBS backed EC2 Instance is ‘True’. Root volume can be preserved on termination by changing the ‘DeleteOnTermination’ attribute to false as below :
aws ec2 modify-instance-attribute --instance-id INSTANCEID --block-device-mappings "[{\"DeviceName\": \"/dev/sda1\",\"Ebs\":{\"DeleteOnTermination\":false}}]"
