EBS vs. EFS: Choosing the Right File Storage
By the end of this lesson, you'll be able to:
- Recall EBS's role as block storage, without re-learning it from scratch
- Explain what Amazon EFS provides and how it differs from EBS
- Decide between EBS and EFS for a described multi-instance scenario
Prerequisites: "Static Website Hosting on S3"
EBS, briefly revisited
Module 3 covered EBS in full — block storage, commonly attached to a single EC2 instance, behaving much like a disk or volume that instance's operating system relies on. This lesson doesn't re-teach that; if any of it feels unfamiliar, Module 3's "EBS: Elastic Block Store" lesson is the place to revisit. Here, EBS shows up only as one point of comparison against something new.
EFS: shared file storage for multiple compute resources
Amazon EFS (Elastic File System) is a managed, shared file system — files and directories that multiple compute resources can access concurrently, over the network, rather than being tied to one instance the way an EBS volume typically is. It's Linux-oriented, scales its storage automatically as data grows, and is managed by AWS in the sense that you don't provision a fixed size or manage the underlying storage hardware yourself.
The scenario that makes the EBS/EFS distinction concrete: several application servers need access to the same files at the same time — shared configuration, shared uploaded content, a shared working directory multiple processes read and write to. An EBS volume can't do this — it's built around one instance owning it. EFS can, because shared concurrent access is exactly what it's designed for.
Neither is automatically "the right one"
EFS being capable of shared access doesn't make it automatically the best choice whenever multiple instances are involved — plenty of multi-instance architectures don't need shared file access at all (each instance might be entirely stateless, or might read shared data from S3 instead). The decision comes back to the actual workload requirement: if multiple compute resources genuinely need concurrent access to the same file system, EFS fits; if each instance just needs its own disk, EBS remains the right tool, exactly as Module 3 taught.
A cleanup note, without creating anything
This lesson doesn't ask you to create a real EFS file system — for a beginner module, the reasoning matters more than the hands-on creation, and an unused EFS file system left running after a training exercise is exactly the kind of forgotten resource Module 3 warned about with EBS volumes. If you do experiment with EFS in a real account beyond this course, the same discipline applies: file systems continue to exist (and can continue to have cost implications) until you explicitly remove them — review what you've created, the same way you would for an EC2 instance or EBS volume.
Exercise
Three EC2 application servers need concurrent access to the same set of uploaded files, all servers reading and writing to the same locations. Would EBS or EFS fit this requirement, and why does the other option not work for this specific scenario?
Show hint
Think about whether the requirement is "each instance has its own storage" or "multiple instances share one storage."
EBS vs. EFS: Choosing the Right File Storage Quiz
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Summary
EBS (covered fully in Module 3) is block storage typically attached to one EC2 instance at a time, while EFS is a shared, managed Linux file system that multiple compute resources can access concurrently — the right choice between them depends on whether your workload genuinely needs shared, simultaneous file access.