S3 vs EFS
Compare object storage with managed shared file storage in AWS.
Storage
Amazon S3
Amazon S3 is object storage built for durability, scale, and API-driven access. It is ideal for files, backups, assets, and data that does not need traditional shared filesystem semantics.
Storage
Amazon EFS
Amazon EFS is a managed shared file system for Linux workloads in AWS. It supports filesystem-style access and can be mounted by multiple compute instances at the same time.
Key Differences
S3 is object storage, while EFS is a shared network file system.
EFS can be mounted by multiple instances like a normal filesystem, while S3 is accessed through object APIs.
S3 is better for large-scale file and object storage, while EFS is better when applications need shared file access semantics.
EFS supports filesystem behavior such as directories and POSIX-style access patterns, while S3 is not a traditional filesystem.
S3 is generally more cost-efficient for durable object storage, while EFS is more specialized and typically more expensive.
The real difference is whether the application needs object storage behavior or shared filesystem behavior.
When to Use
When to use S3
Use S3 for backups, static content, media, logs, archives, and durable storage where applications access data as objects rather than mounted filesystems.
When to use EFS
Use EFS when multiple compute instances need concurrent shared file access through a mounted filesystem.
Tradeoffs
S3 is simpler and more scalable for object storage, but does not provide shared filesystem semantics.
EFS provides shared mounted storage, but costs more and is not a replacement for general-purpose object storage.
S3 is ideal for storage-at-scale, while EFS is ideal for shared-file workloads.
Common Mistakes
Using EFS when the workload only needs durable object storage.
Using S3 for applications that require mounted shared filesystem access.
Assuming both solve the same storage access model because both store files.
Interview Tip
The short answer is: S3 is object storage, EFS is shared file storage.