EFS vs EBS cost: shared file storage vs attached block storage

Quick answer

EBS is block storage attached to a single EC2 instance, billed per provisioned GB whether or not you use it; EFS is a fully managed shared file system that many instances mount simultaneously, billed per GB actually stored with elastic scaling. EFS costs more per GB than EBS but requires no capacity provisioning and scales automatically, while EBS is cheaper per GB but you pay for provisioned (not used) capacity and it attaches to only one instance. Choose EBS for single-instance block storage like boot and database volumes, and EFS for shared file access across many instances, using EFS Infrequent Access tiers to cut cost.

EFS and EBS solve different storage problems, and comparing them on price alone misses the point. EBS is block storage for one instance; EFS is a shared file system for many. EFS costs more per GB, but it removes the provisioning and scaling work EBS requires. The right choice is usually dictated by access pattern first, with cost as the tiebreaker within the right category.

The fundamental difference

Aspect	EBS	EFS
Type	Block storage, one instance	Shared file system, many instances
Billing	Per provisioned GB	Per GB actually stored
Capacity	You provision and grow it	Elastic, scales automatically
Per-GB price	Lower	Higher (standard tier)
Access	Single instance at a time	Concurrent from many instances

EBS bills for provisioned capacity: allocate a 500 GB volume and you pay for 500 GB even if you store 50. EFS bills for what you actually store and grows and shrinks automatically. So EFS's higher per-GB rate is partly offset by paying only for real usage and never over-provisioning, while EBS's lower rate comes with the obligation to size volumes yourself.

When EBS is the right (and cheaper) choice

Use EBS for single-instance block storage: boot volumes, database data volumes, and any workload where one instance needs fast, low-latency block access. For these, EBS is both the correct type and cheaper per GB, provided you right-size the volume rather than over-provisioning. Choosing gp3 over gp2 (see gp2 vs gp3) and watching snapshot cost creep keep EBS spend efficient.

When EFS earns its higher rate

Use EFS when many instances need to read and write the same files concurrently: shared content across a web server fleet, shared home directories, container storage mounted by many tasks, and lift-and-shift applications expecting a shared file system. EBS cannot do this (it attaches to one instance), so EFS is not just more expensive, it is the only fit. The value is the managed shared access and automatic scaling, which you would otherwise build yourself.

Cutting EFS cost with tiers

EFS offers storage classes that dramatically lower cost for the right access pattern. Standard is for frequently-accessed files; Infrequent Access (IA) and Archive tiers cost far less per GB for rarely-touched data, with a small per-access retrieval charge. Lifecycle management moves files to cheaper tiers automatically based on access age, so cold data stops paying the standard rate. One-Zone variants trade multi-AZ redundancy for a lower price where that is acceptable. These tiers are the main EFS cost lever, analogous to the class choices in GCP storage classes and Glacier vs Deep Archive.

The decision

Let access pattern decide first: one instance needs block storage, use EBS; many instances need shared file access, use EFS. Then optimize within the choice, right-size EBS volumes and pick gp3; enable EFS lifecycle tiering and consider One-Zone. Paying the EFS premium only makes sense when you genuinely need shared access; forcing a single-instance workload onto EFS wastes money, and forcing a shared workload onto EBS does not work at all. For the storage share of a full application bill, see how much it costs to run a website on AWS.

FAQ

Is EFS more expensive than EBS?

Per GB, yes: EFS's standard tier costs more per GB than EBS. But EFS bills only for data actually stored and scales automatically, while EBS bills for provisioned capacity whether used or not, so EFS's higher rate is partly offset by avoiding over-provisioning. The real comparison depends on access pattern: EFS provides shared multi-instance access that EBS cannot, so they are not interchangeable.

What is the difference between EFS and EBS?

EBS is block storage attached to a single EC2 instance, which you provision and grow yourself. EFS is a fully managed shared file system that many instances mount concurrently, scaling elastically and billing for actual usage. EBS suits single-instance block storage like boot and database volumes; EFS suits shared file access across many instances, such as a web server fleet sharing content.

When should I use EFS instead of EBS?

When many instances need to read and write the same files concurrently: shared content across a web fleet, shared home directories, container storage mounted by many tasks, or lift-and-shift apps expecting a shared file system. EBS attaches to only one instance and cannot serve this, so EFS is the only fit, not merely the pricier option. For single-instance block storage, use EBS.

How do I reduce EFS costs?

Use EFS storage tiers. Standard is for frequently-accessed files; Infrequent Access and Archive tiers cost far less per GB for rarely-touched data, with a small retrieval charge. Enable lifecycle management to move files to cheaper tiers automatically by access age, and consider One-Zone variants where multi-AZ redundancy is not required. These tiers are the primary EFS cost lever.

Can EBS be shared across multiple instances?

Standard EBS volumes attach to a single instance at a time. EBS Multi-Attach exists for specific io1 and io2 volumes and cluster-aware applications, but it is limited and not a general shared file system. For genuine concurrent file access across many instances, EFS is the right tool. If your workload needs shared access, that requirement, not price, should drive you to EFS.

Does EFS charge for data you do not use?

No. Unlike EBS, which bills for provisioned capacity whether or not you fill it, EFS bills only for the data actually stored and scales elastically. This means you never over-provision EFS capacity. Combined with lifecycle tiering that moves cold data to cheaper Infrequent Access and Archive tiers, EFS lets you pay closely for real usage, which partly offsets its higher standard per-GB rate.

What to do next

Price your storage architecture before you build it. C3X reads your Terraform and prices your resources against a live catalog. Start with the quickstart.