S3:
https://docs.aws.amazon.com/s3/?id=docs_gateway
emrfs:
https://docs.aws.amazon.com/emr/latest/ManagementGuide/clone-console.html
缩小ebs容量：
https://cloudacademy.com/blog/amazon-ebs-shink-volume/
监控s3流量：
https://docs.aws.amazon.com/zh_cn/AmazonS3/latest/dev/cloudwatch-monitoring.html
https://docs.aws.amazon.com/zh_cn/AmazonS3/latest/user-guide/configure-metrics.html