EC2 Instance Storage Options: EBS, EFS, and Instance Store

As you work with EC2 instances, one of the most crucial aspects is understanding the different storage options available. Storage is essential for your applications to store data, configurations, and other necessary files, and choosing the right one can significantly impact performance, availability, and cost efficiency.

In this article, we’ll explore the three primary storage options available for EC2 instances:

1. Elastic Block Store (EBS)
2. Elastic File System (EFS)
3. Instance Store

We will dive into the differences, use cases, and best practices for each of these storage options.

1. Elastic Block Store (EBS)

EBS is a scalable and persistent block storage service used to store data for EC2 instances. EBS volumes behave like hard drives, providing highly available and durable storage that can be attached to any EC2 instance. The best part? EBS volumes persist even when the instance is stopped or terminated.

Key Features of EBS:

• Persistence: Data stored in EBS volumes is persistent, meaning it remains even after the instance is stopped or terminated.
• Performance: EBS offers a range of performance options. You can choose the volume type based on your application's needs, including general-purpose SSDs (gp3), provisioned IOPS SSDs (io2), and throughput-optimized HDDs (st1).
• Scalability: EBS volumes can be easily resized to scale up as your application grows.
• Snapshots: You can create backups of your EBS volumes by taking snapshots, which can be stored in Amazon S3.

Types of EBS Volumes:

1. General Purpose SSD (gp3): Balanced performance for most workloads.
2. Provisioned IOPS SSD (io2): Designed for I/O-intensive applications, offering low-latency and high-throughput.
3. Throughput Optimized HDD (st1): Best suited for large, sequential I/O workloads like big data analytics.
4. Cold HDD (sc1): Low-cost storage for infrequently accessed data.
5. Magnetic (standard): Legacy storage type for low-cost use cases (not recommended for new applications).

When to Use EBS?

• When you need persistent storage that survives EC2 instance reboots and terminations.
• For applications that require high I/O performance like databases, file systems, or big data applications.
• When you need backups or the ability to create snapshots.

Example: Attaching an EBS Volume to EC2

Here’s an example of how to attach an EBS volume to your EC2 instance using the AWS Console:

1. In the EC2 Dashboard, navigate to Volumes under the Elastic Block Store section.
2. Click Create Volume.
3. Select the volume type (e.g., gp3, io2), size, and availability zone.
4. After the volume is created, click on Actions > Attach Volume and select the instance to attach it to.

2. Elastic File System (EFS)

EFS is a scalable file storage solution that can be accessed concurrently by multiple EC2 instances. It provides a network file system that can be mounted onto EC2 instances, allowing them to share file-based data.

Key Features of EFS:

• Scalable: EFS automatically scales to meet your storage needs. It can grow or shrink as your files are added or deleted.
• Shared Access: EFS allows multiple EC2 instances to access the same file system concurrently, making it ideal for applications that require shared storage.
• Fully Managed: AWS manages the infrastructure, so you don’t need to worry about the operational overhead of scaling or maintaining file storage.
• Performance: EFS provides scalable performance and supports two performance modes:
  1. General Purpose: Suitable for latency-sensitive applications.
  2. Max I/O: Suitable for applications requiring high throughput, like big data processing.

When to Use EFS?

• For shared access to files across multiple EC2 instances.
• When you need file-based storage that can scale automatically and be accessed by multiple instances.
• For use cases like web hosting, content management systems, and big data analytics.

Example: Mounting an EFS to EC2 Instance

1. Create an EFS file system from the AWS Console.
2. After the file system is created, attach it to the VPC where your EC2 instances reside.
3. From your EC2 instance, mount the EFS using the provided DNS name:

   sudo mount -t efs fs-xxxxxxxx:/ /mnt/efs

3. Instance Store (Ephemeral Storage)

An Instance Store is temporary storage that is physically attached to the host machine where your EC2 instance runs. Instance Store is also referred to as ephemeral storage, meaning that data stored on an instance store is lost if the instance is stopped, terminated, or fails.

Key Features of Instance Store:

• Temporary Storage: Data is lost if the instance is stopped or terminated.
• High Performance: Instance Store provides very high I/O throughput, making it suitable for temporary data storage that doesn’t need to persist across instance restarts.
• Cost-Effective: It comes at no additional cost as it is included with certain instance types.

When to Use Instance Store?

• For temporary data storage, such as cache data, scratch space, or temporary files.
• For applications that require high-performance I/O throughput but don’t require data persistence.
• Suitable for containerized applications that don’t require data persistence between reboots.

Example: Using Instance Store with EC2

If your EC2 instance type supports Instance Store (e.g., i3, m3, or c5d), the instance will automatically have ephemeral storage configured. You can access it via the /dev/nvme1n1 directory:

lsblk
sudo mount /dev/nvme1n1 /mnt/instance-store

Choosing the Right Storage for Your EC2 Instance

Here’s a quick decision guide for selecting the right storage for your EC2 instance based on your use case:

Storage Type	Use Case	Pros	Cons
EBS	Persistent data storage	Highly durable, backup & snapshot features	Costly for high-performance workloads
EFS	Shared file storage for multiple instances	Scalable, multiple EC2 instances can access	Higher latency than EBS, can be costlier
Instance Store	Temporary, high-performance storage	Extremely fast I/O	Data is lost if instance is stopped/terminated

Best Practices for EC2 Storage:

• For persistent data that should survive reboots or terminations, use EBS.
• For shared file systems between multiple EC2 instances, use EFS.
• For temporary, high-performance storage, use Instance Store for caching and scratch space.

Conclusion

Choosing the right storage option is crucial to the success of your EC2-powered application. EBS is best for persistent, high-performance storage, while EFS is ideal for sharing data between multiple EC2 instances. Instance Store provides extremely fast I/O for temporary data that doesn’t need to survive instance reboots.

In the next article, we’ll discuss advanced EC2 features like Elastic Load Balancing (ELB), Auto Scaling, and Security Groups in more detail to help you optimize your infrastructure for high availability and fault tolerance.

Stay tuned for more!