Question 1

What's the difference between EFS and EBS?

Accepted Answer

EBS (Elastic Block Store) is block storage that is typically attached to one EC2 instance at a time (like a virtual hard drive). EFS is a shared file system that many instances can mount simultaneously over the network (like a shared office drive). Use EBS for low-latency block storage for a single server (databases, boot volumes). Use EFS when multiple servers need to read/write the same files at the same time.

Question 2

When should I use EFS?

Accepted Answer

Use EFS when you need shared, POSIX-style file storage across multiple EC2 instances or containers. Common cases include shared web content across a fleet of web servers, shared user uploads, shared application assets, CI/CD build artifacts, and shared home directories. If you only need object storage for files (not a mounted file system), Amazon S3 is often a better fit.

Question 3

How much does EFS cost?

Accepted Answer

EFS pricing is primarily based on how much data you store (GB-month) and, depending on the throughput mode and access patterns, may include charges related to throughput and/or requests. Costs also vary by storage class (for example, standard vs. infrequent access) and region. To estimate accurately, consider: total stored data, how often data is accessed, expected throughput, and whether lifecycle policies move data to lower-cost storage classes.

EFS

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