Amazon EFS Made Easy: The File System That Scales With You

Have you ever wanted to share files across multiple EC2 instances without copying them manually or worrying about storage limits? That’s exactly what Amazon EFS (Elastic File System) is for.

In this blog, we’ll explain EFS in simple terms, show where it fits in the AWS ecosystem, and cover the important stuff: performance modes, storage classes, cost, and real-world use cases.

🌐 What is Amazon EFS?

Amazon EFS is a fully managed, scalable file system for Linux-based workloads. It’s built on the NFS (Network File System) protocol, which means multiple EC2 instances — even in different Availability Zones — can access the same files at the same time.

Key Benefits:

✅ Shared access across EC2s
📦 No need to pre-provision storage – it grows/shrinks automatically
🌍 High availability – works across multiple AZs
🔒 Supports encryption at rest and in transit
🧠 Only for Linux-based EC2 instances (not supported on Windows)

Real-life analogy: Think of EFS as a shared team drive in the cloud that can grow as big as you need, and everyone on your team (EC2s) can use it at the same time.

📂 How Does It Work?

You create an EFS file system and control access using security groups.

Then, your EC2 instances (in any AZ within the same region) mount this file system using NFS, and they can read and write files together — perfect for shared data environments like web servers or applications that need to work with the same files.

🧰 Common Use Cases

WordPress hosting
Shared web content
Development environments
Big data analytics
Media processing
Machine learning input/output

⚙️ Performance Modes (Choose at File System Creation)

Think of Performance Mode as choosing how your EFS file system behaves under pressure. Do you need it to respond quickly for small, fast requests? Or do you want it to handle massive amounts of traffic even if it's a bit slower?

You choose a Performance Mode when you create the EFS, because it defines how the system is optimized behind the scenes. This decision cannot be changed later, so it’s important to pick the right one based on your use case.

EFS supports two performance modes. You pick one when you create the file system:

1. General Purpose (default)

🕒 Low latency = fast responses
✅ Best for: web servers, CMS, dev tools
🧠 Use this in most situations unless you're doing something really large-scale

2. Max I/O

🚚 Supports thousands of connections
🐢 Slightly slower response (higher latency)
✅ Best for: big data jobs, media processing, analytics workloads

📌 Exam Tip: If you see “low latency” in a question — pick General Purpose. If you see “high throughput or large-scale parallel access” — go with Max I/O.

📊 Throughput Modes

Throughput is about how much data EFS can read/write per second — like the width of a highway. More throughput = more “cars” (data) passing through per second.

Choosing the right throughput mode helps balance performance and cost. If your workload has unpredictable traffic or needs consistent speed, you’ll want to configure this wisely.

You can change the Throughput Mode after creating the file system, unlike performance mode. EFS supports three throughput modes:

1. Bursting Throughput (default)

🚀 Auto-scales based on how much data you store
✅ Good for most apps with consistent or average usage
💡 Example: A small web app that sees spikes occasionally

Analogy: Like a normal road that adds extra lanes when there's traffic.

2. Provisioned Throughput

📏 You set the speed, no matter how much data is stored
✅ Best for apps that need high throughput even with little stored data
💡 Example: A data processing app that doesn’t store much but reads/writes a lot fast

Analogy: Like building a wide highway from the start — even if you only use a small part of it.

3. Elastic Throughput

🤖 Automatically adjusts to your needs
✅ Best for unpredictable or bursty workloads
💡 Example: A machine learning app that runs big jobs occasionally

Analogy: Like a smart road that expands and shrinks lanes instantly, based on the number of cars.

🗄️ Storage Classes in EFS

To help you save costs, EFS offers multiple storage classes — like a tiered storage system:

1. EFS Standard

For frequently accessed files
Highest cost, highest performance

2. EFS Infrequent Access (EFS-IA)

For files you rarely use
Much cheaper to store, slightly slower to access
You pay a small fee to retrieve files

3. EFS Archive

For rarely accessed, cold data
Even cheaper, but slower to access

🔁 Lifecycle Management: Move Data Automatically

You don’t have to move files manually between storage tiers!

With lifecycle policies, EFS can automatically move files to IA or Archive after they haven’t been accessed for a certain number of days (7, 14, 30, 60, 90).

Example:

File stored in EFS Standard
Not accessed for 60 days
EFS moves it to EFS-IA to save you money 💰

🏗️ Multi-AZ vs One-Zone

Multi-AZ (Standard)

High availability
Ideal for production apps

One-Zone

Cheaper option
Less availability (stored in one AZ)
Good for dev/test environments

✅ You can still use IA with One-Zone to save even more.

💰 Cost Considerations

Yes, EFS is more expensive than EBS (about 3x more than gp2 per GB). But it offers:

No capacity planning
Auto scaling
Pay-per-use pricing (you only pay for storage used)

Combine Standard + IA + Lifecycle Management = up to 90% savings!

🧠 Summary Cheat Sheet (AWS Exam Friendly!)

Feature	Description
Protocol	NFS
OS Compatibility	Linux only
Availability	Multi-AZ and One-Zone options
Performance Modes	General Purpose, Max I/O
Throughput Modes	Bursting, Provisioned, Elastic
Storage Classes	Standard, Infrequent Access, Archive
Lifecycle Mgmt	Move files between tiers automatically
Use Cases	WordPress, dev tools, shared file storage, big data
Encryption	Supports encryption at rest (via KMS)

🧩 Final Thoughts

Amazon EFS is a powerful tool when you need multiple EC2s to work with the same files — whether you're hosting a website, running a dev environment, or building a large-scale data pipeline.

Use the right performance mode and storage class, and you’ll get flexibility and savings at the same time.