Difference between Amazon Elastic Block Store (EBS) and EC2 instance storage

Amazon Elastic Block Store (EBS) and EC2 instance storage (often referred to as EC2 instance store or ephemeral storage) are two different types of storage options provided by AWS for use with EC2 instances. Here are the key differences between them:

Amazon Elastic Block Store (EBS)

1. Persistence:

   • Persistent Storage: EBS volumes are designed to be durable and persist independently of the EC2 instance’s lifecycle. Data remains on the volume until it is explicitly deleted.

2. Durability and Availability:

   • Redundancy: EBS volumes are automatically replicated within their Availability Zone to protect against hardware failures, providing high durability and availability.
   • Snapshots: You can take point-in-time snapshots of EBS volumes, which are stored in Amazon S3. These snapshots can be used to create new volumes or to back up data.

3. Types and Performance:

   • Types: EBS offers various volume types, including General Purpose SSD (gp3, gp2), Provisioned IOPS SSD (io1, io2), Throughput Optimized HDD (st1), and Cold HDD (sc1). These types provide different performance characteristics and cost points.
   • Performance: EBS volumes can be tuned for different levels of performance, with some types providing high IOPS and low latency, suitable for databases and high-performance applications.

4. Flexibility and Features:

   • Attach/Detach: EBS volumes can be attached to and detached from EC2 instances, allowing for flexible use and data management.
   • Size and Performance Adjustments: EBS volumes can be resized and their performance characteristics can be modified without downtime.

5. Cost:

   • Billing: EBS volumes are billed based on the provisioned capacity and performance characteristics, regardless of the actual usage.

EC2 Instance Storage (Instance Store)

1. Persistence:

   • Ephemeral Storage: Instance store volumes are ephemeral and data is lost if the instance is stopped, terminated, or fails. These volumes are ideal for temporary storage needs where data loss is acceptable.

2. Durability and Availability:

   • Non-Persistent: Instance store volumes are directly attached to the physical hardware of the host machine and do not offer redundancy or replication. Data is only available while the instance is running.

3. Types and Performance:

   • Performance: Instance store provides very high I/O performance and low latency because it is physically attached to the host machine. It is suitable for temporary storage, caching, or other scenarios where performance is critical but persistence is not required.

4. Flexibility and Features:

   • Limited Flexibility: Instance store volumes are fixed in size and cannot be detached or reattached to other instances. They are not designed for long-term storage or for data that needs to persist beyond the instance’s lifecycle.
   • No Snapshots: There is no built-in mechanism to take snapshots or backups of instance store volumes.

5. Cost:

   • Included with EC2: The cost of instance store volumes is included in the price of the EC2 instance. There is no additional charge for using instance storage, making it cost-effective for temporary data.