Amazon Elastic File System (EFS) Cheatsheet

What is Amazon EFS?

Amazon EFS (Elastic File System) is a fully-managed, serverless, elastic NFS file system service that makes it easy to set up, scale, and cost-optimize file storage in the AWS Cloud.

Key Features

Fully-managed service: No file storage infrastructure to provision or manage
NFS compatibility: Supports Network File System version 4 (NFSv4) protocol
Elastic scaling: Automatically grows and shrinks as you add and remove files
Multi-AZ redundancy: Data and metadata stored redundantly across multiple AZs
Shared access: Allows thousands of concurrent NFS connections
Petabyte scale: Can grow to petabyte scale with high throughput
Linux & macOS support: Mount on EC2 instances running Linux or macOS Big Sur (Windows not supported)
Integration with AWS services: Mount on ECS tasks, EKS pods, and Lambda functions
Security: POSIX permissions and IAM-based access control
Data consistency: Strong data consistency and file locking support

Storage Classes

Storage Class	Description	Use Case
Standard	Default storage class with highest performance	Active file workloads
Infrequent Access (IA)	Lower cost storage for less frequently accessed files	Files accessed less than once per 30 days
One Zone	Standard storage in a single AZ	Lower-cost option for easily reproducible data
One Zone-IA	Infrequent access storage in a single AZ	Lowest cost option for infrequently accessed data

Performance Modes

Mode	Description	Best For
General Purpose (default)	Lower latency, good for most workloads	Web serving, CMS, home directories
Max I/O	Higher throughput and IOPS with slightly higher latency	Big data, media processing, scientific analysis

Throughput Modes

Mode	Description	Best For
Bursting (default)	Throughput scales with file system size	Varied or unpredictable workloads
Provisioned	Specify throughput independent of storage size	Predictable performance requirements
Elastic	Automatically scales throughput up or down	Applications with variable performance needs

Access Points

Simplify application access to shared datasets
Enforce operating system user, group, and directory for every request
Work with IAM for granular access control
Provide isolated application-specific view of the file system

Mounting EFS File Systems

Prerequisites:

# Install EFS client on Amazon Linux or Amazon Linux 2
sudo yum install -y amazon-efs-utils

# Install on Ubuntu/Debian
sudo apt-get -y install git binutils
git clone https://github.com/aws/efs-utils
cd efs-utils
./build-deb.sh
sudo apt-get -y install ./build/amazon-efs-utils*deb

Mount Commands:

# Basic mount using EFS mount helper
sudo mount -t efs fs-12345678:/ /mnt/efs

# Mount with encryption in transit
sudo mount -t efs -o tls fs-12345678:/ /mnt/efs

# Mount via DNS name
sudo mount -t nfs4 -o nfsvers=4.1,rsize=1048576,wsize=1048576,hard,timeo=600,retrans=2,noresvport fs-12345678.efs.us-east-1.amazonaws.com:/ /mnt/efs

# Mount using Access Point
sudo mount -t efs -o tls,accesspoint=fsap-12345678 fs-12345678:/ /mnt/efs

Automount with fstab:

# Add to /etc/fstab
fs-12345678:/ /mnt/efs efs defaults,tls 0 0

Security Best Practices

Enable encryption at rest and in transit
Use IAM roles for EC2 instances accessing EFS
Configure NFS client firewall rules
Use security groups to control network access
Apply principle of least privilege with Access Points
Set proper POSIX permissions on files and directories
Enable AWS CloudTrail to audit API calls

Monitoring and Management

CloudWatch Metrics:

BurstCreditBalance: Available burst credits
PermittedThroughput: Allowed throughput in MiB/s
TotalIOBytes: I/O operations in bytes
DataWriteIOBytes: Write operations in bytes
DataReadIOBytes: Read operations in bytes
MeteredIOBytes: Billable I/O operations in bytes
StorageBytes: Size of file system by storage class

Data Migration and Backup:

Use AWS DataSync for efficient data transfer between on-premises and EFS
Use EFS-to-EFS backup solution for scheduled incremental backups
AWS Backup integrates with EFS for automated backups
Configure Lifecycle Management to move infrequently accessed files to IA storage class

Pricing Considerations

Pay only for storage used (no pre-provisioning)
Standard storage: Higher cost, best performance
IA storage: Up to 85% lower cost for infrequently accessed files
One Zone storage: Lower cost by storing in a single AZ
Throughput pricing based on mode selected
Cost savings through appropriate lifecycle management policies

When to Use EFS vs Alternative Services

EFS vs EBS:

Choose EFS when you need shared access from multiple instances across AZs
Choose EBS for single-instance access with lowest latency requirements

EFS vs S3:

Choose EFS for file system access semantics and hierarchical structure
Choose S3 for object storage with web-scale access patterns

Common Use Cases

Content Management Systems
Web Serving
Application Development Environments
Database Backups
Media Processing Workflows
Big Data and Analytics
Home Directories
Container Storage
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