Understanding the Differences Between EBS and EFS in AWS

When working with Amazon Web Services (AWS), understanding the distinctions between EBS (Elastic Block Store) and EFS (Elastic File System) is crucial for selecting the right storage solution for your application. This article breaks down their key differences, use cases, and important considerations.

📌 Amazon EBS (Elastic Block Store)

EBS is a block storage service that provides persistent storage for EC2 instances. It is best suited for single-instance storage needs where high performance and low latency are required.

🔹 Key Features of EBS

1. Instance Attachment
   • An EBS volume is typically attached to a single EC2 instance.
   • The exception is multi-attach support for io1/io2 volumes, which allows sharing between multiple instances but is for specific high-performance use cases.
2. Availability Zone (AZ) Bound
   • EBS volumes are locked to a specific Availability Zone (AZ).
   • If you need to move an EBS volume to another AZ, you must:
     1. Take a snapshot of the volume.
     2. Restore the snapshot in the target AZ.
3. I/O Performance
   • gp2 volumes: I/O increases with disk size.
   • gp3 and io1/io2 volumes: I/O performance can be adjusted independently of disk size.
4. Backups & Performance Considerations
   • EBS backups (snapshots) consume I/O, so avoid running backups during peak application traffic to prevent performance degradation.
5. EC2 Termination Behavior
   • By default, root EBS volumes of EC2 instances are deleted when the instance is terminated.
   • This behavior can be disabled if persistent storage is required after termination.

📌 Amazon EFS (Elastic File System)

EFS is a managed, network-based file system designed for multiple EC2 instances to access shared storage simultaneously.

🔹 Key Features of EFS

1. Multi-AZ Support & Shared Access
   • Unlike EBS, EFS is designed to be mounted by multiple EC2 instances across different Availability Zones (AZs).
   • Each AZ has its own mount target, allowing multiple instances to access the same file system.
2. Linux-Only File System
   • EFS is only compatible with Linux instances since it supports POSIX file system standards.
3. Higher Cost but Tiered Storage Options
   • EFS is more expensive than EBS, but AWS offers storage tiers to optimize cost:
     • Standard storage (for frequently accessed data).
     • Infrequent Access (IA) storage (for less-accessed data at a lower cost).

✅ When to Use EFS?

• Best suited for applications requiring shared storage, such as:
  • Content Management Systems (e.g., WordPress).
  • Big Data & analytics workloads that need simultaneous access from multiple instances.