100 Days of AWS – Day 10

 

100 Days of AWS – Day 10: EC2 Storage - EBS vs. Instance Store

Welcome to Day 10! Today we're looking at the "hard drives" for our EC2 instances. Not all storage is created equal, and choosing the right type is crucial for a well-architected application.

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The Question

An application running on an EC2 instance needs an extremely fast, low-latency storage volume for temporary data like caches and scratch files. This data does NOT need to be saved if the instance stops or terminates.

Which EC2 storage option is the best fit for this specific requirement?

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The Correct Answer

The correct answer is (C) Instance Store.

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Why It's Correct: High-Speed, Ephemeral Storage

An Instance Store (also known as Ephemeral Storage) provides temporary, block-level storage for an EC2 instance. Its key characteristic is that it is physically attached to the host machine that your EC2 instance is running on.

This direct attachment gives it two main properties:

1. Extremely High Performance: Because the storage is physically connected, it offers very high IOPS (Input/Output Operations Per Second) and extremely low latency, making it perfect for I/O-intensive tasks.
2. Ephemeral (Temporary): The data on an instance store only persists for the life of the instance. If you stop, hibernate, or terminate the instance, all data on the instance store is permanently deleted.

This makes it the perfect choice for temporary data that can be easily recreated, such as caches, buffers, scratch data, and load-balanced web server assets.

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Analysis of the Incorrect Options

• (A) EBS General Purpose (SSD): Amazon EBS (Elastic Block Store) is a network-attached storage volume. Its primary benefit is persistence—the data on an EBS volume remains even after the instance is stopped. While it offers good performance, it will generally have higher latency than a physically attached Instance Store.
• (B) EFS (Elastic File System): Amazon EFS is a managed network file system that can be shared and accessed by multiple EC2 instances at the same time. It's designed for file sharing and shared content, not for high-performance temporary storage for a single instance.
• (D) S3 (Simple Storage Service): Amazon S3 is object storage, not block storage. You access it via API calls to store and retrieve files. It cannot be used as a root volume or a high-performance scratch disk for an application running on EC2.

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Quick Comparison Table

Feature	EBS (Elastic Block Store)	Instance Store
Persistence	✅ Durable: Data persists when instance stops.	❌ Ephemeral: Data is deleted when instance stops.
Attachment	Network-Attached	Physically Attached
Performance	Good to Excellent (depending on type)	Highest Possible (lowest latency)
Best Use Case	Boot volumes, databases, persistent data	Caches, scratch files, temporary data

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Further Reading

• Official AWS Documentation: Amazon EC2 Instance Store
• Official AWS Documentation: Amazon Elastic Block Store (EBS)

Keywords 

• EBS (Elastic Block Store)
• EC2 Instance Store
• EC2 Storage
• Ephemeral Storage
• Persistent Storage
• AWS Block Storage
• IOPS (Input/Output Operations Per Second)
• Data Persistence
• Low Latency Storage
• EFS (Elastic File System)
• S3 (Simple Storage Service)
• SSD Storage
• "when to use instance store vs ebs"
• "difference between ebs and instance store"
• "what is ephemeral storage in aws"
• "high performance temporary storage for ec2"
• "does ec2 instance store persist data"

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