Amazon EBS vs Amazon ElastiCache: What are the differences?

Introduction

In this article, we will explore the key differences between Amazon Elastic Block Store (EBS) and Amazon ElastiCache. Both of these services are provided by Amazon Web Services (AWS) and are important for different purposes in cloud computing infrastructures.

1. Data Storage vs. In-Memory Caching: The main difference between Amazon EBS and Amazon ElastiCache lies in their primary use cases. Amazon EBS is designed for data storage, serving as a persistent block-level storage volume for EC2 instances. On the other hand, Amazon ElastiCache is a fully managed in-memory caching service that helps improve the performance and scalability of web applications by alleviating the load on databases and disk-based storage.

2. Persistence: Another significant difference between Amazon EBS and Amazon ElastiCache is in terms of persistence. Amazon EBS volumes are persistent, meaning that the data stored on them is retained even after the EC2 instance is stopped or terminated. In contrast, Amazon ElastiCache is not primarily designed for persistence, as it is focused on caching frequently accessed data in-memory for faster retrieval. The data stored in Amazon ElastiCache is not permanently stored and could be evicted from the cache depending on various factors.

3. Storage Volume Types: Amazon EBS offers different types of storage volumes, including General Purpose SSD (GP2), Provisioned IOPS SSD (io1), Throughput Optimized HDD (st1), and Cold HDD (sc1). This variety of volume types allows users to choose the appropriate storage solution based on their workload requirements. On the other hand, Amazon ElastiCache is solely focused on in-memory caching and does not provide different types of storage volumes.

4. Use of Protocols: Amazon EBS uses the network block device (NBD) protocol for communicating with EC2 instances. This protocol enables block-level storage access and allows for increased flexibility and compatibility with various operating systems. In contrast, Amazon ElastiCache uses standard memcached or Redis protocols for cache access, making it compatible with applications that can utilize these protocols.

5. Cost Structure: There is a difference in the cost structure between Amazon EBS and Amazon ElastiCache. Amazon EBS charges users for the provisioned storage volume, I/O operations, and snapshot storage. On the other hand, Amazon ElastiCache pricing is based on the cache node types and the amount of cache memory utilized, with additional charges for data transfer and backup snapshots.

6. Multi-Availability Zone (Multi-AZ) Support: Amazon EBS provides the option for creating multi-AZ volumes, which replicate the data across multiple Availability Zones for high availability and durability. This feature ensures that data is protected in case of an Availability Zone failure. On the other hand, Amazon ElastiCache does not support multi-AZ deployments, as it is primarily focused on caching data for performance improvement rather than high availability.

In summary, the key differences between Amazon EBS and Amazon ElastiCache are their primary use cases (data storage vs. in-memory caching), persistence (EBS is persistent while ElastiCache is not), storage volume types (EBS offers different types, ElastiCache does not), protocols used (EBS uses NBD while ElastiCache uses memcached or Redis), cost structure, and multi-AZ support (EBS supports, ElastiCache does not).