Meaning of EBS - Amazon Elastic Block Store

In the context of Amazon Elastic Block Store (EBS), the term "block" refers to the fundamental unit of data storage and Elastic means we can attach and detach the EBS to any EC2 instance easily and data is stored permanently on EBS. Here's a detailed explanation of what a "block" means and its implications:

Block Storage Overview

Block storage is a type of storage that manages data in fixed-sized chunks called blocks. Each block is identified by a unique address, and these blocks are stored and retrieved individually. This approach is different from object storage (like Amazon S3) or file storage (like Amazon EFS).

Characteristics of Block Storage in EBS

1. Fixed-Size Units:

   • Data in EBS volumes is divided into fixed-size blocks. When you write or read data, you do so in these blocks, not as a whole file or object.

2. Addressable Units:

   • Each block has a unique address, allowing precise control over where data is written or read. This enables efficient updates to small parts of a dataset without needing to read or write the entire dataset.

3. Low-Latency and High Performance:

   • Block storage is designed for low-latency access, making it suitable for high-performance applications such as databases, virtual machines, and transactional systems where quick read/write operations are critical.

4. File Systems and Databases:

   • EBS volumes act like raw, unformatted disks that you can format with a file system (e.g., ext4, NTFS) or use as raw storage for databases. Applications that require structured storage can use these volumes to manage data efficiently.

Practical Implications of Block Storage in EBS

1. Versatility:

   • You can use EBS volumes for a variety of purposes, including:
     • Operating System Boot Volumes: EBS volumes can store the operating system of an EC2 instance, providing persistent storage for system files.
     • Application Data: Applications can use EBS for storing and retrieving application data with low latency.
     • Databases: Databases can use EBS volumes to store data files, ensuring high I/O performance and low latency.

2. Performance:

   • EBS offers different volume types optimized for various performance characteristics:
     • General Purpose SSD (gp2, gp3): Balanced performance for a wide range of workloads.
     • Provisioned IOPS SSD (io1, io2): High performance for I/O-intensive workloads.
     • Throughput Optimized HDD (st1) and Cold HDD (sc1): Cost-effective storage for large, sequential workloads like big data and log processing.

3. Persistence and Reliability:

   • EBS volumes persist independently of the EC2 instance. Data stored on an EBS volume remains intact across instance stops and starts.
   • EBS volumes are automatically replicated within the same Availability Zone to prevent data loss due to hardware failures, ensuring high availability and durability.

Example Scenario

Imagine you have an EC2 instance running a database server. You can attach an EBS volume to this instance to store the database files. Here's how block storage is utilized in this scenario:

• The database software reads and writes data in small chunks (blocks).
• Each block read or write operation is directed to specific addresses on the EBS volume.
• The performance of these operations depends on the type of EBS volume (e.g., gp3 for balanced performance or io2 for high IOPS requirements).