The best feature of Amazon EFS is its ability to share files between multiple servers even if the data is present only in one server. Thus some applications include:
Media Processing and Entertainment - like Netflix,
Database Backups and Disaster Recovery,
Content Management Service - like online photo editor, text editor or video editor, etc.
Workloads should allow shared accessing, should be scalable, should be persistent.
A snapshot ID is auto assigned to the rrot volume during instance creation because the volume ois created from an AMI.and AMI's are backed by EBS Snapshots of the root filesystem