3.2 AWS Storage Services
Key Takeaways
- Amazon S3 is object storage with 99.999999999% (11 nines) durability — the most commonly used storage service on AWS.
- Amazon EBS provides block storage volumes for EC2 instances — like a virtual hard drive that persists independently of the instance.
- Amazon EFS is a fully managed, elastic file system that can be mounted by multiple EC2 instances simultaneously.
- S3 storage classes range from Standard (frequent access) to Glacier Deep Archive (rarely accessed, cheapest) — choose based on access frequency.
- AWS Storage Gateway connects on-premises environments to cloud storage for hybrid workloads.
Quick Answer: AWS has three storage shapes — object (Amazon S3), block (Amazon EBS), and file (Amazon EFS / Amazon FSx). The CLF-C02 tests which one fits a scenario: S3 for internet-scale object data, EBS for an EC2 boot/data disk, and EFS for a shared file system mounted by many instances at once.
The Three Types of Cloud Storage
| Type | Description | AWS Service | Analogy |
|---|---|---|---|
| Object Storage | Flat namespace; files stored as objects with metadata | Amazon S3 | A vast labeled filing system |
| Block Storage | Fixed-size blocks, like a raw virtual hard drive | Amazon EBS | A disk attached to your computer |
| File Storage | Hierarchical directories and files | Amazon EFS, FSx | A network shared drive |
Amazon S3 (Simple Storage Service)
Amazon S3 stores and retrieves any amount of object data from anywhere. Data lives in buckets (containers) as objects (the file plus metadata). It is one of the most heavily tested services on the exam.
S3 Key Features
- Durability: 99.999999999% (11 nines) — designed to survive the simultaneous loss of two facilities
- Availability: 99.99% for S3 Standard
- Scalability: effectively unlimited capacity
- Object size: up to 5 TB per object (multipart upload for large objects)
- Bucket names must be globally unique across all AWS accounts
- Region-scoped: an object is stored in the Region of its bucket and stays there unless you move/replicate it
S3 Storage Classes
| Storage Class | Access Pattern | Min Storage Duration | Retrieval Time | Relative Cost |
|---|---|---|---|---|
| S3 Standard | Frequent access | None | Milliseconds | Highest |
| S3 Intelligent-Tiering | Unknown/changing access | None | Milliseconds | Auto-optimized |
| S3 Standard-IA | Infrequent access | 30 days | Milliseconds | Lower |
| S3 One Zone-IA | Infrequent, non-critical (one AZ) | 30 days | Milliseconds | Lower still |
| S3 Glacier Instant Retrieval | Rarely accessed, instant needed | 90 days | Milliseconds | Low |
| S3 Glacier Flexible Retrieval | Archive | 90 days | Minutes to hours | Very low |
| S3 Glacier Deep Archive | Long-term archive | 180 days | Up to 12 hours | Lowest |
On the Exam: Frequent = Standard. Unknown/changing = Intelligent-Tiering (it moves objects between tiers automatically for you). Infrequent = IA. Archive with instant need = Glacier Instant Retrieval. Deep cold archive = Deep Archive. Watch the minimum storage duration — storing a short-lived object in Glacier can cost more due to the 90/180-day minimum charge.
S3 Key Concepts
| Concept | Description |
|---|---|
| Versioning | Keep multiple versions of an object; protects against accidental overwrite/delete |
| Lifecycle Policies | Auto-transition objects between classes or expire them after a set time |
| Replication | Cross-Region Replication (CRR) or Same-Region Replication (SRR) for compliance/DR |
| Encryption | Server-side (SSE-S3 default, SSE-KMS, SSE-C) or client-side |
| Access Control | Bucket policies, IAM policies, S3 Access Points; Block Public Access on by default |
| Static Website Hosting | Serve a static site directly from a bucket |
Since 2023, S3 encrypts every new object with SSE-S3 by default, and Block Public Access is enabled on new buckets by default — both are common "secure by default" exam facts.
Amazon EBS (Elastic Block Store)
Amazon EBS provides persistent block-storage volumes for EC2 — effectively a virtual hard drive you attach to an instance.
EBS Key Facts
- Volumes persist independently of the instance lifecycle (survive stop/start)
- Volumes are AZ-specific — they attach only to instances in the same Availability Zone
- Snapshots are point-in-time backups stored in S3 and are incremental (only changed blocks)
- Volumes can be encrypted with AWS KMS, including all snapshots and data in transit to the instance
- A single gp3/io2 volume can scale up to 64 TiB
EBS Volume Types
| Type | Category | Use Case |
|---|---|---|
| gp3 / gp2 | General Purpose SSD | Boot volumes, dev/test, most workloads (gp3 is the current default) |
| io2 / io1 | Provisioned IOPS SSD | High-performance/transactional databases |
| st1 | Throughput Optimized HDD | Big data, log processing, streaming |
| sc1 | Cold HDD | Infrequent access, lowest-cost HDD |
On the Exam: EBS = block storage for EC2; AZ-scoped. S3 = object storage; Region-scoped, accessed over HTTP/API. If data must survive instance termination, the answer is EBS or S3 — not instance store.
Amazon EFS (Elastic File System)
Amazon EFS is a fully managed, elastic NFS file system for Linux workloads.
| Feature | Detail |
|---|---|
| Protocol | NFS v4 |
| OS Support | Linux (use FSx for Windows/SMB) |
| Scaling | Grows and shrinks automatically; pay for what you use |
| Access | Mounted concurrently by many EC2 instances across AZs |
| Availability | Multi-AZ by default within a Region |
| Use Cases | Content management, shared application files, web serving |
Amazon FSx
Amazon FSx delivers fully managed third-party file systems:
| Service | File System | Use Case |
|---|---|---|
| FSx for Windows File Server | Windows NTFS (SMB) | Windows apps needing SMB shares |
| FSx for Lustre | Lustre | HPC, ML training, high-throughput compute |
| FSx for NetApp ONTAP | NetApp ONTAP | Enterprise migrations from on-premises NetApp |
| FSx for OpenZFS | OpenZFS | Linux workloads needing ZFS features |
AWS Storage Gateway and Hybrid Storage
AWS Storage Gateway connects on-premises applications to AWS storage (File Gateway, Volume Gateway, Tape Gateway). It is the answer when a scenario describes "keep using on-prem servers but back up or tier to the cloud."
Storage Comparison
| Feature | S3 | EBS | EFS |
|---|---|---|---|
| Type | Object | Block | File |
| Scope | Region | Single AZ | Region (Multi-AZ) |
| Access | API/HTTP | One EC2 instance* | Many EC2 instances |
| Max Size | 5 TB per object (unlimited total) | 64 TiB per volume | Petabytes |
| Durability | 11 nines | 99.999% | 11 nines |
| Pricing | Per GB stored + requests | Per GB provisioned | Per GB used |
*EBS Multi-Attach (io1/io2) lets a volume attach to several instances, but only within one AZ.
On the Exam: "Shared file system for many instances" = EFS. "Boot disk / database disk for one instance" = EBS. "Store and serve files/objects to the internet at scale" = S3.
What level of durability does Amazon S3 Standard provide?
A company needs to archive data that is rarely accessed and can tolerate retrieval times of up to 12 hours. Which S3 storage class is MOST cost-effective?
What is the key difference between Amazon EBS and Amazon S3?
Which AWS storage service allows multiple EC2 instances to share a file system simultaneously?