Amazon Elastic File System
EFS
You need a shared, POSIX-compliant network file system that hundreds of virtual servers can mount and access at once.
Reach for it when
- Sharing configuration files, media uploads, or application code across a autoscaling fleet of EC2 instances.
- Hosting legacy applications that require concurrent file read/write operations from multiple servers.
- Providing persistent shared directories for container tasks running on ECS or EKS.
Do not reach for it when
- Providing local block storage for a single database instance requiring high IOPS and low latency — use EBS instead.
- Storing unstructured media assets or data backups that do not require POSIX mounting — use S3 instead.
- Mounting storage to Windows-based virtual machine instances — use Amazon FSx for Windows File Server instead.
Alternatives, and how to choose
| Service | Pick it instead when |
|---|---|
| EBS | Choose it when you need high-performance block storage dedicated to a single virtual machine. |
| S3 | Choose it when storing massive volumes of unstructured object files at a lower storage cost. |
How you pay
- The model
- Pay per GB stored per month, with separate tiers for standard access and infrequent access.
- The line item that surprises people
- Enabling provisioned throughput instead of elastic throughput can result in high, unexpected fixed monthly fees.
What trips people up
- Standard EFS performance scales with storage size; small filesystems have low burst credit limits and throttle performance.
- Accessing EFS across different AWS regions is slow and incurs significant inter-region network transfer fees.
- Failing to configure security groups on EFS mount targets will block EC2 instances from mounting the filesystem.
Verify the live service
This page is a concept reference. Cost models are qualitative; confirm the current offering, Region and pricing before deploying.