Understanding AWS EBS Block Storage: A Beginner’s Guide

When you launch an EC2 instance, the first thing you’ll need is reliable storage. Amazon Elastic Block Store (EBS) provides persistent, high‑performance block storage that works like a traditional hard drive but with the flexibility of the cloud. In this guide we’ll break down what EBS is, the different volume types, pricing basics, and best‑practice tips to get the most out of your block storage.

What Is AWS EBS?

AWS EBS is a fully‑managed block‑level storage service designed for use with Amazon EC2. Unlike Amazon S3, which is object storage, EBS volumes behave like raw disks that you can format, mount, and use as file systems or raw block devices.

• Persistent: Data remains even after the attached instance stops or terminates (unless you delete the volume).
• Scalable: You can provision from 1 GiB up to 16 TiB per volume.
• Durable: EBS replicates data within its Availability Zone (AZ) to protect against hardware failures.

Key Features to Know

1. Snapshots

Snapshots capture a point‑in‑time copy of a volume and are stored in Amazon S3. They are incremental, meaning only changed blocks are saved, which reduces cost and speeds up backup operations.

2. Encryption

EBS supports encryption at rest and in transit using AWS Key Management Service (KMS). Encryption is transparent – you don’t need to modify your applications.

3. Performance Modes

EBS offers two performance modes: General Purpose SSD (gp3/gp2) for balanced workloads and Provisioned IOPS SSD (io2/io1) for high‑throughput, low‑latency needs.

Volume Types Overview

Volume Type	Use Case	Performance	Typical Cost (USD/GB‑mo)
gp3 (General Purpose SSD)	Web servers, dev/test, small databases	Up to 16 000 IOPS, 1 000 MiB/s	~0.08
gp2 (General Purpose SSD)	Legacy workloads	Up to 10 000 IOPS, 250 MiB/s	~0.10
io2 (Provisioned IOPS SSD)	High‑transaction databases, SAP	Up to 64 000 IOPS, 1 000 MiB/s	~0.125 + $0.065 per provisioned IOPS
io1 (Provisioned IOPS SSD)	Similar to io2, older generation	Up to 64 000 IOPS	~0.12 + $0.065 per provisioned IOPS
st1 (Throughput‑Optimized HDD)	Big data, data warehouses	Up to 500 MiB/s	~0.045
sc1 (Cold HDD)	Infrequent access, archival	Up to 250 MiB/s	~0.025

How to Choose the Right Volume

1. Identify workload patterns: Transactional DBs need high IOPS (io2/io1), while log storage can use st1.
2. Estimate required IOPS and throughput: Use AWS’s “EBS Performance Calculator” to match volume size with IOPS.
3. Consider cost vs. performance: gp3 offers a predictable price with the ability to burst IOPS, making it a safe default.
4. Plan for scaling: You can increase volume size, IOPS, or switch types without downtime using elastic resize.

Best Practices for Performance & Durability

• Spread I/O across multiple volumes: Distribute workloads over several EBS volumes to avoid a single‑volume bottleneck.
• Use RAID 0 for throughput‑intensive apps: Combine two or more gp3 volumes to achieve higher sequential throughput.
• Enable Multi‑AZ snapshots: Copy snapshots to another region for disaster recovery.
• Monitor with CloudWatch: Track VolumeReadOps, VolumeWriteOps, and BurstBalance to detect throttling.
• Regularly prune old snapshots: Delete unnecessary snapshots to reduce storage costs.

Pricing Snapshot (US East 1)

EBS pricing is based on three components:

1. Volume storage per GB‑month.
2. Provisioned IOPS (if applicable).
3. Snapshot storage per GB‑month.

For a 500 GiB gp3 volume with default 3 000 IOPS, the monthly cost is roughly 500 × 0.08 = $40. Adding 5 TiB of snapshots would add about 5 000 × 0.05 = $250.

FAQ

Can I attach an EBS volume to multiple EC2 instances?

Only with EBS Multi‑Attach (io1/io2) and within the same AZ. It’s useful for clustered databases.

What happens to data if I delete the EC2 instance?

The volume remains unless you selected “Delete on termination.” You can re‑attach it to another instance.

How often should I take snapshots?

For production databases, daily incremental snapshots plus a weekly full backup is a common strategy.

Is EBS suitable for latency‑sensitive applications?

Yes, especially Provisioned IOPS SSD (io2/io1) which guarantees up to 64 000 IOPS with sub‑millisecond latency.

Can I change a volume type after provisioning?

Yes. Use the “Modify Volume” API or console to switch types without detaching.

Conclusion

AWS EBS Block Storage provides the flexibility of cloud economics with the reliability of traditional disks. By selecting the appropriate volume type, monitoring performance, and following snapshot best practices, you can build fast, durable, and cost‑effective applications on EC2.

Call to Action

Ready to optimize your EC2 storage? Contact our cloud architects today for a free assessment and a custom EBS sizing plan.