Amazon EBS
Amazon Elastic Block Store (EBS) — persistent block storage for EC2. Covers volume types (gp3, io2, st1, sc1), IOPS vs throughput trade-offs, and cross-cloud equivalents.
Overview
Amazon Elastic Block Store (EBS) provides persistent block-level storage volumes for use with Amazon EC2 instances. EBS volumes behave like raw, unformatted block devices — attached to an EC2 instance and used like a physical disk.
Key properties:
- Availability Zone (AZ)-scoped — a volume exists in one AZ and can only be attached to instances in that same AZ
- Persistent — data persists independently of the EC2 instance lifecycle (survives stop/start)
- Snapshots — point-in-time backups stored in Amazon S3; can be used to create volumes in any AZ
SAA/SAP Tip: EBS is AZ-bound. To move data across AZs, create a snapshot and restore it in the target AZ (or use Amazon EFS for shared, multi-AZ file storage).
Volume Types
SSD-Backed (IOPS-optimized)
| Volume Type | Use Case | IOPS | Throughput | Volume Size | Durability | Cost |
|---|---|---|---|---|---|---|
| gp3 (General Purpose SSD) | Default for most workloads | 3,000 free; max 16,000 (extra cost) | 125 MB/s free; max 1,000 MB/s (extra cost) | 1 GiB – 16 TiB | 99.8–99.9% | Moderate |
| gp2 (General Purpose SSD, legacy) | Older default; IOPS tied to volume size | 100 – 16,000 (3 IOPS/GiB) | 128–250 MB/s | 1 GiB – 16 TiB | 99.8–99.9% | Moderate |
| io2 Block Express (Provisioned IOPS SSD) | I/O-intensive workloads: critical OLTP, SAP HANA | Max 256,000 | Max 4,000 MB/s | 4 GiB – 64 TiB | 99.999% | Highest |
| io1 (Provisioned IOPS SSD, legacy) | Critical OLTP, latency-sensitive | Max 64,000 | Max 1,000 MB/s | 4 GiB – 16 TiB | 99.8–99.9% | High |
HDD-Backed (Throughput-optimized)
| Volume Type | Use Case | Max IOPS | Max Throughput | Volume Size | Boot Volume? | Cost |
|---|---|---|---|---|---|---|
| st1 (Throughput Optimized HDD) | Big data, log processing, large sequential reads | 500 | 500 MB/s | 125 GiB – 16 TiB | No | Low |
| sc1 (Cold HDD) | Infrequently accessed cold data | 250 | 250 MB/s | 125 GiB – 16 TiB | No | Lowest |
Exam Trap: st1 and sc1 volumes cannot be used as boot volumes.
Only SSD-backed volumes (gp2, gp3, io1, io2) support booting an EC2 instance.
SAA/SAP Tip: Prefer gp3 over gp2 for new workloads — gp3 is ~20%
cheaper at baseline and allows independent scaling of IOPS and throughput
without increasing volume size. With gp2, IOPS are locked to 3 IOPS/GiB.
Latency Characteristics
| Category | Volume Type | Latency |
|---|---|---|
| SSD (General Purpose) | gp3, gp2 | Single-digit milliseconds |
| SSD (Provisioned IOPS) | io2, io1 | Sub-millisecond |
| HDD | st1, sc1 | Not suited for latency-sensitive workloads |
Key SAA/SAP Exam Tips
SAA/SAP Tip: When a scenario requires highest IOPS with lowest latency
(e.g., database with millions of transactions), choose io2 Block Express.
When single-digit millisecond latency and cost-efficiency matter most, choose
gp3.
SAA/SAP Tip: For big data / MapReduce / log processing, st1 is the
correct answer — high throughput at low cost.
Exam Trap: Multi-Attach (attaching one EBS volume to multiple EC2
instances simultaneously) is only supported for io1 and io2 volumes, and
only within the same AZ.
Cross-Cloud Equivalents
| Provider | Service / Solution | Notes |
|---|---|---|
| AWS | Amazon EBS | Baseline |
| Azure | Azure Disk Storage | Similar tiered SSD (Premium, Standard) / HDD model; zone-pinned like EBS |
| GCP | Persistent Disk / Hyperdisk | Hyperdisk Extreme for high-IOPS workloads; similar tier structure |
| On-Premises | Local HDD / SSD, SAN, NAS | Direct-attached or network storage; no built-in HA or snapshot management |
| Akamai | Akamai Block Storage | S3-compatible block storage for Akamai cloud instances |
| DigitalOcean | DigitalOcean Block Storage (Volumes) | SSD-backed; simpler tier model |
Pricing Model
- Billed per GB-month provisioned (not consumed)
- Additional charge for provisioned IOPS above baseline (io1, io2, gp3 above 3,000)
- Additional charge for provisioned throughput above baseline (gp3 above 125 MB/s)
- Snapshots billed per GB-month stored in S3
Related Services / See Also
- Amazon EC2 — EBS volumes attach to EC2 instances
- Amazon EFS — managed NFS file storage; multi-AZ, shared access
- Amazon S3 — object storage; used for EBS snapshots
- Database Performance Fundamentals — IOPS vs throughput explained
AWS WAF and Shield
Web application firewall and DDoS protection — web ACLs, rate limiting, managed rules, Shield Standard vs Advanced.
Amazon EFS and FSx
AWS managed file storage services — Amazon EFS (Elastic File System) for Linux-based NFS workloads, and Amazon FSx for Windows, Lustre, NetApp ONTAP, and OpenZFS. Covers use cases, performance modes, and cross-cloud equivalents.