What it is: A managed file system that can be mounted by multiple instances at the same time (NFS).

What it’s for:

• Shared storage for fleets of EC2 instances or containers.
• Content management, shared app files.

Key ideas:

• Unlike EBS (attached to one instance), EFS can be shared by many.
• Typically used inside a VPC with mount targets per AZ.

Exam cues:

• “multiple EC2 instances need shared file system” → EFS.

Hard words:

• *mount* /maʊnt/: gắn (file system vào máy)
• *shared* /ʃerd/: dùng chung
• *fleet* /fliːt/: một nhóm lớn (nhiều máy)