Module Objective: Distinguish object, block, and file storage; describe Amazon S3's storage classes and data management features; and identify which AWS storage service fits a given workload.
Builds on Module 6 — storage is what compute resources like Amazon EC2 instances read from and write to.
Storage Types: Object, Block, and File
AWS storage services fall into three broad categories, each suited to a different access pattern.
| Type | How Data Is Accessed | AWS Example |
|---|---|---|
| Object storage | Whole files ("objects") retrieved by a unique key, over HTTP(S) | Amazon S3 |
| Block storage | Raw, fixed-size blocks of data, attached to a single compute instance like a hard drive | Amazon EBS |
| File storage | A shared, hierarchical file system mounted and accessed by multiple compute instances at once | Amazon EFS |
🔵 Why It Matters
Choosing the wrong storage type for a workload — for example, trying to share a block volume across many instances — is a common architecture mistake. The access pattern a workload needs is usually the fastest way to narrow down the right service.
Amazon S3 Fundamentals
Amazon Simple Storage Service (S3) is AWS's object storage service, designed for 99.999999999% ("11 nines") of durability by automatically storing data redundantly across multiple Availability Zones within a Region.
| Concept | What It Is |
|---|---|
| Bucket | A container for objects, created in a specific Region, with a globally unique name |
| Object | A file plus its metadata, stored under a unique key within a bucket |
| Durability vs. availability | Durability describes the odds data survives long-term; availability describes how reliably it can be accessed at any given moment — S3 publishes separate targets for each |
✅ Tip — S3 Is Not a File System
S3 has no true folder structure — what looks like folders in the console are really just key names containing slashes (e.g.
images/logo.png). This is part of why S3 scales so well for object access, but it's a different mental model than a traditional file system.
Amazon S3 Storage Classes
S3 offers multiple storage classes trading retrieval speed and flexibility for lower storage cost, so the same durability applies at very different price points depending on how often data is actually accessed.
| Storage Class | Best For |
|---|---|
| S3 Standard | Frequently accessed data |
| S3 Intelligent-Tiering | Data with unknown or changing access patterns; automatically moves objects between tiers |
| S3 Standard-IA (Infrequent Access) | Data accessed less often but needed quickly when it is |
| S3 One Zone-IA | Infrequently accessed, re-creatable data that doesn't need multi-AZ resilience |
| S3 Glacier Instant/Flexible/Deep Archive | Long-term archival, with retrieval times ranging from milliseconds to many hours depending on tier |
⚠️ Warning — Lower Storage Cost, Higher Retrieval Cost
The cheapest storage classes generally carry higher retrieval fees and longer retrieval times. Choosing a storage class is a trade-off based on real access patterns, not simply picking the lowest per-GB storage price.
Amazon S3 Data Management Features
Beyond storing objects, S3 includes built-in features for protecting and automatically managing data over its lifetime.
| Feature | What It Does |
|---|---|
| Versioning | Keeps multiple versions of an object, protecting against accidental overwrites or deletes |
| Lifecycle policies | Automatically transitions objects to cheaper storage classes, or deletes them, after a defined time period |
| Replication | Automatically copies objects to another bucket, in the same or a different Region |
| Encryption | Objects can be encrypted at rest, using AWS-managed or customer-managed keys via AWS KMS (Module 4) |
🔵 Note
Lifecycle policies are a common way to reduce storage cost automatically — for example, moving log files to S3 Standard-IA after 30 days and to Glacier Deep Archive after a year, without any manual intervention.
Amazon EBS (Block Storage)
Amazon Elastic Block Store (EBS) provides persistent block storage volumes that attach to a single EC2 instance, functioning much like a virtual hard drive.
| Concept | What It Means |
|---|---|
| Persistence | An EBS volume's data survives independently of the instance's running/stopped state |
| AZ-bound | A volume exists in a single Availability Zone and can only attach to instances in that same AZ |
| Snapshots | Point-in-time, incremental backups of a volume, stored in Amazon S3, that can be used to create new volumes in any AZ within the Region |
✅ Tip — Snapshots Cross AZ Boundaries, Volumes Don't
Because a volume can't move between AZs directly but a snapshot can be used to create a new volume anywhere in the Region, snapshots are the standard mechanism for migrating or recovering EBS data across AZs.
Amazon EFS and Amazon FSx (File Storage)
File storage services provide a shared file system that multiple compute instances can mount and access concurrently — something neither S3 nor EBS is designed for.
| Service | What It Is |
|---|---|
| Amazon Elastic File System (EFS) | A fully managed, scalable NFS file system that can be mounted by many EC2 instances across multiple AZs at once |
| Amazon FSx | A family of fully managed file systems built on popular third-party file system technologies, such as Windows File Server and Lustre |
🔵 Note
EFS automatically grows and shrinks as files are added or removed, with no capacity to provision up front — unlike an EBS volume, which has a fixed provisioned size.
Hybrid Storage: AWS Storage Gateway
AWS Storage Gateway connects on-premises applications to AWS storage, letting existing on-premises systems use cloud storage without significant application changes.
| Gateway Type | Use Case |
|---|---|
| File Gateway | Presents Amazon S3 as an on-premises file share |
| Volume Gateway | Presents cloud-backed iSCSI block storage volumes to on-premises servers |
| Tape Gateway | Presents a virtual tape library, letting existing backup software archive to the cloud instead of physical tape |
✅ Tip — A Bridge, Not Just a Migration Tool
Storage Gateway is often used as an ongoing hybrid solution — not only as a one-time migration path — for organizations that need some data to remain accessible on-premises indefinitely.
Choosing the Right Storage Service
As with compute in Module 6, the right storage service depends on the specific access pattern and durability/availability needs of the workload.
| Need | Likely Fit |
|---|---|
| Store and serve static website assets, backups, or data lake content | Amazon S3 |
| Boot volume or database storage for a single EC2 instance | Amazon EBS |
| Shared file system accessed by many instances at once | Amazon EFS or Amazon FSx |
| Connect existing on-premises backup software to the cloud | AWS Storage Gateway |
| Infrequently accessed data that must be retained for compliance | Amazon S3 Glacier storage classes |
🔵 Note
It's common for a single application to use several storage services together — for example, EBS for the operating system and database, S3 for backups and static assets, and EFS for shared configuration files.
Key Terms for Module 7
- object storage
- Storage accessed as whole files ("objects") retrieved by a unique key over HTTP(S), e.g. Amazon S3
- block storage
- Raw, fixed-size blocks of storage attached to a single compute instance, e.g. Amazon EBS
- file storage
- A shared, hierarchical file system mountable by multiple compute instances at once, e.g. Amazon EFS
- bucket
- A container for objects in Amazon S3, created in a specific Region with a globally unique name
- S3 storage class
- A tier trading retrieval speed/flexibility for storage cost, e.g. Standard, Standard-IA, Glacier
- lifecycle policy
- An S3 rule that automatically transitions or deletes objects after a defined time period
- Amazon EBS
- AWS's persistent block storage service, providing volumes attached to a single EC2 instance within one AZ
- snapshot
- A point-in-time, incremental backup of an EBS volume, stored in Amazon S3
- Amazon EFS
- A fully managed, scalable NFS file system mountable by many EC2 instances across AZs
- AWS Storage Gateway
- A hybrid storage service connecting on-premises applications to AWS storage
Review Questions
- What is the key difference in access pattern between object, block, and file storage?
- What is the difference between durability and availability as Amazon S3 defines them?
- Why might an organization use an S3 lifecycle policy instead of manually managing which storage class each object uses?
- Why can't an Amazon EBS volume attach directly to an instance in a different Availability Zone, and how does a snapshot solve that problem?
- What need does Amazon EFS meet that neither Amazon S3 nor Amazon EBS is designed to meet?
- What problem does AWS Storage Gateway solve for an organization with existing on-premises backup infrastructure?
- For a data lake holding infrequently accessed compliance records that must be retained for seven years, which storage service and class would likely fit best, and why?