AWS Storage — Complete Reference¶

1. Storage Types — The Big Picture¶

AWS Storage
├── Block Storage     → EBS, Instance Store     (low-latency, OS/database)
├── Object Storage    → S3                       (scalable, internet-accessible)
└── File Storage      → EFS, FSx                 (shared, multi-instance)

Rule: Storage type determines access pattern, not just "where data lives." Match storage type to workload behavior — wrong choice = bottleneck or wasted cost.

2. Block Storage¶

Data stored as fixed-size blocks — like a physical hard drive. Access is direct, low-latency, and operates below the filesystem level.

2.1 Amazon EBS (Elastic Block Store)¶

Definition: Persistent, network-attached block storage volumes for EC2 instances.

2.1.1 EBS Volume Types — Performance Numbers ⭐¶

2.1.2 gp2 vs gp3 — Why Always Use gp3 ⭐¶

Always choose gp3 over gp2. It is cheaper, faster (for most sizes), and more predictable. gp2 small volumes (<334 GB) rely on burst credits — performance becomes unpredictable.

2.1.3 io2 vs gp3 — When is io2 Worth the Cost?¶

gp3 at 16,000 IOPS (200 GB):   ~$81/month
io2 at 16,000 IOPS (200 GB):   ~$1,065/month   (≈13× more expensive)

Pay for io2 only when you need: - More than 16,000 IOPS (io2 goes up to 64,000 / Block Express to 256,000) - 99.999% durability (five nines — for mission-critical databases) - Sub-millisecond consistent latency (Oracle, SAP HANA, SQL Server) - Multi-Attach — attach to multiple instances simultaneously

2.1.4 Boot (Root Volume) Support¶

2.1.5 IOPS vs Throughput — Clarified ⭐¶

Small random reads/writes (databases, OS) → care about IOPS
Large sequential reads/writes (logs, big data) → care about Throughput

2.1.6 EBS Root Volume Behavior¶

Disabling DeleteOnTermination on root volume = EBS persists after instance termination. Data volumes: DeleteOnTermination is disabled by default.

2.1.7 EBS Multi-Attach (io1/io2 only) ⭐¶

• Attach one EBS volume to multiple EC2 instances simultaneously (same AZ)
• Only io1 and io2 support this
• Use case: clustered databases (Oracle RAC, DRBD) that manage concurrent access
• Application must handle concurrent writes — EBS does NOT manage write conflicts

2.1.8 EBS Snapshots ⭐¶

Point-in-time backups of EBS volumes — stored in S3 (managed by AWS, not your bucket).

# Create snapshot
aws ec2 create-snapshot --volume-id vol-xxxxxxxx --description "my backup"

# Copy to another Region
aws ec2 copy-snapshot --source-region us-east-1 --source-snapshot-id snap-xxxxxxxx --region eu-west-1

Snapshot best practices: - Use Amazon Data Lifecycle Manager (DLM) for automated snapshot schedules - Enable EBS Snapshot Archive for 75% cheaper long-term retention (restore takes hours) - Enable Recycle Bin to protect against accidental deletion (1–365 day retention)

2.1.9 EBS Encryption¶

Encrypted volume → all snapshots encrypted. Encrypted snapshot → all volumes created from it are encrypted. You cannot directly encrypt an existing unencrypted volume — copy snapshot → encrypt copy → create volume.

2.1.10 Mount Points (Volume Identification)¶

Modern AWS instances (Nitro-based, all current gen) use NVMe device names.

2.1.11 Attach / Detach Rules¶

2.2 Instance Store (Ephemeral Storage)¶

Definition: Temporary block storage physically attached to the host machine your EC2 runs on.

Behavior by action:

Use cases: Temporary cache, buffer, scratch space, batch intermediate results, replica data.

EBS vs Instance Store — Decision Guide¶

3. Object Storage — Amazon S3¶

Definition: Store data as objects (file + metadata + unique key) in buckets.

S3 Storage Classes (Cost vs Access):

4. File Storage¶

Shared filesystem accessible by multiple instances simultaneously — like a NAS.

4.1 Amazon EFS (Elastic File System)¶

Definition: Managed NFS (Network File System) for Linux workloads.

4.2 Amazon FSx (Managed Specialty File Systems)¶

Definition: Fully managed file systems for specific use cases requiring specialty protocols.

FSx for Lustre can directly integrate with S3 — reads/writes back to S3 bucket automatically. FSx for Windows = the answer whenever a question mentions SMB, Windows Server, or Active Directory.

5. Complete AWS Storage Comparison ⭐¶

6. Workload → Storage Mapping¶

7. EC2 Storage Architecture Patterns¶

Pattern 1 — Standard Web Server¶

EC2 Instance
├── EBS gp3 (root) → OS + app code
└── EBS gp3 (data) → logs, config

Pattern 2 — High Performance Database¶

EC2 Instance
├── EBS gp3 (root)  → OS
└── EBS io2         → database data files (high IOPS + 99.999% durability)

Pattern 3 — Batch Processing (Cost-Optimized)¶

EC2 Spot Instance
└── Instance Store → scratch space during processing
    S3             → input data source + output destination

Pattern 4 — Shared Application (Multi-Server)¶

EC2 Instance 1 ─┐
EC2 Instance 2 ─┼── EFS (shared NFS) → shared config, uploads
EC2 Instance 3 ─┘
     │
     └── EBS gp3 (per instance) → OS

8. Common Mistakes ✅¶

9. Interview Questions Checklist ✅¶

• Name the 3 types of AWS storage — example of each
• What is EBS? What are its key properties?
• List all EBS volume types with IOPS and throughput limits
• gp2 vs gp3 — why always choose gp3?
• gp3 vs io2 — when does io2 justify the cost?
• What is the difference between IOPS and Throughput?
• Which EBS volume types are bootable?
• What is EBS Multi-Attach? Which volume types support it?
• What are EBS Snapshots? Are they incremental?
• Where are EBS Snapshots stored?
• How do you move an EBS volume to another AZ? Another Region?
• What happens to EBS when an EC2 instance is terminated?
• What is Instance Store? When is data lost?
• Instance Store vs EBS — key differences
• What is EFS? Which OS does it support?
• EFS vs FSx — when to use which?
• FSx types — which for Windows? Which for HPC?
• What is S3? What durability does it offer?
• Name S3 storage classes — cheapest for archival?
• You need shared storage for 3 Linux EC2 instances — what do you use?
• You need high-speed temp storage for batch jobs — what do you use?
• How do you encrypt an existing unencrypted EBS volume?