Amazon Elastic File System (Amazon EFS) provides a simple, scalable, elastic file system for general purpose workloads for use with AWS Cloud services and on-premises resources.OR

Amazon EFS (Elastic File System) is a shared file storage service in AWS.
It allows multiple EC2 instances to access the same files at the same time.

Think of EFS like:

Google Drive for your EC2 servers.

---

What problem EFS solves

Without EFS:

• Every EC2 has its own storage

• Files are not shared

With EFS:

• All EC2 see the same files

• Data stays in sync

---

Why EFS is used

EFS is used when:

• Many servers need same data

• You want shared storage

• You need scalable file system

• You want managed NFS storage

---

Where EFS is used

EFS is used in:

• Web applications

• Media storage

• WordPress

• Microservices

• CI/CD shared workspace

• Kubernetes persistent storage

• Big data processing

---

When to use EFS

Use EFS when:

• You have multiple EC2

• You need file sharing

• You want automatic scaling

• You want no disk management

Do NOT use EFS when:

• You need very low latency block storage
  Use EBS instead

---

How EFS works

EC2 connects to EFS using:

• NFS protocol

EFS is mounted like:

/mnt/efs

All servers read and write from same folder.

---

EFS vs EBS

---

Key features of EFS

Fully managed

AWS handles:

• Storage

• Replication

• Availability

---

Highly available

Data is stored across:

• Multiple Availability Zones

---

Auto scaling

No size planning needed
It grows and shrinks automatically

---

Secure

Supports:

• Encryption

• IAM access

• Security groups

---

Performance modes

• General Purpose

• Max I/O

---

Throughput modes

• Bursting

• Provisioned

• Elastic

---

Backup

EFS supports:

• AWS Backup

• Snapshots

---

DevOps usage

EFS is used in:

• Kubernetes volumes

• Jenkins shared workspace

• Docker persistent storage

• App log storage

---

Real example

You have 5 web servers
All need same images
Use EFS
Upload once
All servers see it

---

Pricing

You pay only for:

• Storage used

---

Important interview points

• EFS is file storage

• Works with NFS

• Multi AZ

• Shared

• Auto scaling

How to Mount EFS

Step 1: Create EFS

AWS Console → EFS → Create file system
Choose:

• Same VPC as EC2

• Keep defaults

After creating, note:

• File System ID
  Example:

fs-0ab12cd3456ef7890

---

Step 2: Security Group setup

EFS security group must allow:

EC2 security group must allow:

---

Step 3: Install EFS utils on EC2

Login to EC2.

For Amazon Linux:

sudo yum install amazon-efs-utils -y

For Ubuntu:

sudo apt install nfs-common -y

---

Step 4: Create mount directory

sudo mkdir /mnt/efs

---

Step 5: Mount EFS

Replace your file system ID:

sudo mount -t efs fs-0ab12cd3456ef7890:/ /mnt/efs

Check:

df -h

You should see EFS mounted.

---

Step 6: Test

cd /mnt/efs
touch test.txt
ls

If file appears, EFS is working.

---

Step 7: Auto mount after reboot

Edit fstab:

sudo nano /etc/fstab

Add this line:

fs-0ab12cd3456ef7890:/ /mnt/efs efs defaults,_netdev 0 0

Save and exit.

Test:

sudo mount -a

---

What just happened

Now:

• EFS is connected to EC2

• Data will persist

• Multiple EC2 can use same EFS

---

Real DevOps use

This is used in:

• Jenkins

• WordPress

• Kubernetes

• Shared logs

• Microservices