Use the AWS Disk Space dashboard to monitor EBS volumes to see whether they are running out of disk space and take appropriate action to anticipate future storage needs. Amazon Web Services does not report disk space by default.
For more information on accessing additional metrics, including disk space, and corresponding pricing, go to the Amazon Web Services documentation page at http://docs.aws.amazon.com/AmazonCloudWatch/latest/DeveloperGuide/mon-scripts.html.