AWS Storage Services
Identify AWS storage services
What you will learn
- Distinguish object storage (S3) from block storage (EBS) in model and use.
- Choose the right S3 storage class based on data's expected access frequency.
- Explain why a single EC2 instance cannot "own" an S3 bucket exclusively the way it owns an EBS volume.
- Connect S3's high data durability to its use for backup and archiving.
Storage in AWS is not one service but two fundamentally different models: object storage (S3), where files are accessed over the network from anywhere without being tied to a specific instance, and block storage (EBS), where a virtual disk is attached to a single EC2 instance as part of its system.
The core services
| Amazon S3 | Object storage designed for very high durability and near-unlimited scale, accessed via HTTP from anywhere. |
|---|---|
| Amazon EBS | Block storage typically attached to a single EC2 instance, as a virtual hard drive that is part of its system. |
| Amazon EFS | A shared file system multiple EC2 instances can access simultaneously — unlike EBS, which is tied to a single instance. |
S3 vs. EBS
| Amazon S3 | Amazon EBS | |
|---|---|---|
| Access | Via HTTP from anywhere, no specific EC2 instance needed | Attached to a single EC2 instance as part of its system |
| Typical use | Static files, backups, archives | The OS disk or database data an EC2 instance operates on |
Choosing an S3 storage class
Audit logs that must be kept for seven years for regulatory reasons, but will very rarely, if ever, be retrieved — this is an ideal S3 Glacier scenario: very low storage cost in exchange for accepting a longer retrieval time on the rare occasion they're needed.
What matters on the exam
- "Accessed from anywhere with no specific instance" points to S3, and "the OS disk of a single instance" points to EBS.
- Cheaper S3 classes (like Glacier) are always slower to retrieve — no class is both cheaper and faster at once.
EFS is not just "a bigger EBS"
The difference isn't size but sharing: EBS is typically attached to only one instance at a time, while EFS is designed from the ground up for multiple EC2 instances to access simultaneously — a question mentioning "several servers needing the same shared files" points to EFS, not EBS.
Quick check
Answer in your head first, then reveal.
What is the fundamental difference between S3 and EBS?Reveal the answer
S3 is object storage accessed from anywhere; EBS is block storage attached to a single instance.
Which S3 class suits a very rarely accessed archive?Reveal the answer
S3 Glacier.
Which service fits when several EC2 instances need to access the same files together?Reveal the answer
Amazon EFS.
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Sources
Used to verify the facts. The writing is original to Passuit.