Amazon Elastic File System (EFS)
- What it is
- Fully managed, elastic NFS file system for Linux workloads.
- Grows and shrinks automatically as files are added and removed — no capacity to provision.
- Key traits
- Mounted by thousands of EC2 instances concurrently, across multiple Availability Zones in a Region.
- Regional by default (multi-AZ redundancy); a One Zone class exists for cheaper, less durable use.
- Storage classes: Standard and Standard-IA, with lifecycle management to move cold files automatically.
- Not to be confused with
- Amazon Elastic Block Store (EBS) — one instance, one AZ, fixed provisioned size.
- Amazon FSx — for Windows (SMB) or specialized high-performance file systems; EFS is Linux/NFS only.
- Amazon S3 — object storage over HTTP, not a mountable POSIX file system.
- Exam signal
- “Shared file storage for multiple Linux EC2 instances” → EFS.