AWS Solutions Architect · Lesson

EFS: Shared File Storage for Linux

Mount an EFS file system across multiple EC2 instances and Lambda functions, configure performance and throughput modes, and control access with security groups.

What Is Amazon EFS?

Amazon Elastic File System (EFS) is a fully managed, elastic, shared POSIX file system that can be mounted by thousands of EC2 instances, Lambda functions, and ECS/EKS containers simultaneously. Unlike EBS (which attaches to a single instance), EFS provides a shared file system where all connected clients see the same files in real time. Capacity grows and shrinks automatically — you never provision storage upfront. EFS is ideal for content management, shared code repositories, home directories, and data analytics.

EFS Storage Classes

EFS offers two storage classes: EFS Standard (multi-AZ, highest availability, sub-millisecond latency) and EFS One Zone (single AZ, 47% lower cost, slightly less resilient). Within each tier, there is also an Infrequent Access (IA) variant that stores data at 92% lower cost than Standard for files that are not accessed regularly. The difference from S3: EFS is a full POSIX file system that your applications can mount — it is not an object store.

# Create an EFS file system in Standard storage class
aws efs create-file-system \
  --performance-mode generalPurpose \
  --throughput-mode elastic \
  --encrypted \
  --tags Key=Name,Value=SharedFileSystem

# One Zone (cheaper, single-AZ):
aws efs create-file-system \
  --performance-mode generalPurpose \
  --throughput-mode elastic \
  --encrypted \
  --availability-zone-name us-east-1a \
  --tags Key=Name,Value=SharedFileSystemOneZone

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