Amazon EFS and FSx

While S3 provides object storage and EBS provides block storage, many workloads require shared file storage — a file system that multiple servers can mount and access concurrently. Amazon Elastic File System (EFS) and Amazon FSx address this need.

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Amazon Elastic File System (EFS)

EFS is a fully managed, elastic, POSIX-compliant file system for Linux workloads. It grows and shrinks automatically as you add and remove files — no provisioning required.

Key Features

Feature	Detail
Protocol	NFS v4.0 and v4.1
Elasticity	Automatically scales from zero to petabytes
Concurrency	Thousands of EC2 instances can mount the same file system simultaneously
Availability	Data stored across multiple AZs (Standard) or single AZ (One Zone)
Durability	99.999999999% (eleven 9s) for Standard classes
OS support	Linux only (not Windows)

EFS Storage Classes

Storage Class	Description	Use Case
Standard	Multi-AZ, high availability	Production workloads
Standard-IA	Multi-AZ, lower cost, retrieval fee	Infrequently accessed files
One Zone	Single AZ, lower cost	Dev/test, non-critical workloads
One Zone-IA	Single AZ + infrequent access	Lowest cost for non-critical, rarely accessed files

EFS supports lifecycle management to automatically move files between Standard and IA classes based on access patterns.

Performance Modes

Mode	Description	Best For
General Purpose	Low latency, suitable for most workloads	Web serving, CMS, home directories
Max I/O	Higher aggregate throughput, slightly higher latency	Big data, media processing

Throughput Modes

Mode	Description
Bursting	Throughput scales with file system size; burst credits for spikes
Provisioned	You specify the throughput independently of storage size
Elastic	Automatically scales throughput up and down based on workload demand

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Creating an EFS File System

# Create the file system
aws efs create-file-system \
  --performance-mode generalPurpose \
  --throughput-mode elastic \
  --encrypted \
  --tags Key=Name,Value=my-shared-fs

# Create a mount target in each AZ
aws efs create-mount-target \
  --file-system-id fs-0123456789abcdef0 \
  --subnet-id subnet-abc123 \
  --security-groups sg-xyz789

Mounting EFS on an EC2 Instance

Using the EFS mount helper (recommended):

# Install the EFS utilities
sudo yum install -y amazon-efs-utils

# Mount with encryption in transit
sudo mount -t efs -o tls fs-0123456789abcdef0:/ /mnt/efs

# Add to fstab for automatic mounting
echo 'fs-0123456789abcdef0:/ /mnt/efs efs _netdev,tls 0 0' | sudo tee -a /etc/fstab

EFS with Containers

EFS integrates with Amazon ECS and EKS as a persistent volume:

• ECS: Define an EFS volume in the task definition.
• EKS: Use the EFS CSI driver to mount file systems as Kubernetes PersistentVolumes.

This enables stateful containers that share data across tasks or pods.

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EFS Access Points

Access points are application-specific entry points into an EFS file system. Each access point can enforce: