Free SAA-C03 practice scenarios: EBS vs S3 vs EFS

Block, object or file — the storage choice the exam poses constantly, and the access pattern that decides it. Seven scenarios, SAA-C03, 2026 edition.

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Storage selection is one of the highest-frequency SAA-C03 patterns, and it turns on a single question: how is the data accessed? Block, object and file are three different access models, and the requirement almost always names the one it needs.

The three models

Block (Amazon EBS) — a volume attached to one EC2 instance in one Availability Zone. Boot volumes and self-managed databases live here: low latency, single-attach.
File (Amazon EFS / FSx) — a shared POSIX file system many instances mount at once. EFS is NFS for Linux across AZs; FSx for Windows File Server is SMB with Windows/Active Directory features; FSx for Lustre is for high-performance compute.
Object (Amazon S3) — reached over an HTTP API, effectively unlimited and highly durable. User uploads, backups, static assets.

The tell words: “shared across instances” → file; “boot volume” or “database data volume” → block; “uploaded files served to browsers”, “unlimited”, “durable” → object.

The distractors that catch people

Two traps recur. First, offering S3 “mounted as a drive” where a real POSIX file system is needed — S3 is an object store, not a mountable file system for concurrent read-write. Second, offering EBS for a fleet — an EBS volume attaches to a single instance, so it can never be the shared file system a multi-instance scenario asks for. When you see “many instances, same files”, the answer is EFS (or FSx for Windows), never EBS.

Picking an EBS volume type

When the question is already inside EBS, the volume type turns on IOPS versus throughput:

io2 (Provisioned IOPS SSD) — high random IOPS for transactional databases, at a premium.
gp3 (General Purpose SSD) — balanced default for most workloads.
st1 (Throughput Optimized HDD) — cheap, high sequential throughput for logs and big-data streaming.
sc1 (Cold HDD) — lowest cost for infrequently accessed data.

Random small reads and writes → io2; large sequential streams on a budget → st1.

The edge cases: FSx and instance store

Two options exist to catch the specific stem. FSx for Windows File Server is the answer whenever the words Windows or SMB appear — EFS is Linux/NFS. And an instance store is the answer for disposable scratch data that wants the highest local I/O at no extra cost and does not mind being lost when the instance stops.

How to use the seven scenarios below

Answer each one before opening the explanation, and when you miss, name the access pattern that decided it — “shared across instances”, “boot volume”, “unlimited objects”, “Windows SMB”, “disposable scratch”. Every explanation states that pattern and then dismantles the distractors, which are usually real storage services answering a different access model. For the domain overview, see Design High-Performing Architectures.

Three storage models compared. Amazon EBS is block storage attached to a single EC2 instance in one Availability Zone, used for boot volumes and databases. Amazon EFS is an elastic NFS file system mounted by many Linux instances across Availability Zones at once, with Amazon FSx serving the Windows SMB and Lustre equivalents. Amazon S3 is object storage reached over an HTTP API, effectively unlimited and highly durable, for uploads, backups and static assets.

7 free SAA-C03 practice questions

Answers and explanations — no email wall

SAA-C03 Question 1 of 7

A fleet of Linux EC2 instances across multiple Availability Zones must all read and write the same set of files concurrently, as a shared file system. Which storage service fits?

Answer: A — Amazon EFS.

Amazon EFS is an elastic NFS file system that many Linux instances can mount and share concurrently across Availability Zones — exactly a shared, multi-AZ file system. Why not the others: an EBS volume attaches to a single instance in a single AZ, so it cannot be the shared file system for a fleet. S3 is object storage accessed over an API, not a POSIX file system you mount for concurrent read-write. Instance store is ephemeral and instance-local. Shared file access across instances is EFS.

SAA-C03 Question 2 of 7

A self-managed relational database on EC2 needs low-latency block storage attached to that one instance, with consistent IOPS. Which storage type is appropriate?

Answer: A — An Amazon EBS volume.

A database needs block storage with low, consistent latency attached to its instance, which is precisely what Amazon EBS provides. Why not the others: EFS is a shared file system over NFS, which adds network file-system overhead a latency-sensitive database does not want. S3 is object storage reached over HTTP — not a block device a database engine can use as its data volume. Glacier is cold archival storage with retrieval times measured in minutes to hours. A database's data volume is EBS.

SAA-C03 Question 3 of 7

A web application stores user-uploaded images and documents that are served to browsers, with unpredictable and effectively unlimited growth, and high durability required. Which storage service is the natural fit?

Answer: A — Amazon S3.

Amazon S3 is object storage designed for effectively unlimited, highly durable storage of files served over HTTP — the standard home for user uploads and static assets. Why not the others: an EBS volume has a fixed provisioned size and attaches to one instance, so it neither scales limitlessly nor serves the web directly. EFS is a shared POSIX file system, more than a web app needs to store objects and pricier per GB. Instance store is ephemeral. Unlimited, durable object storage served over HTTP is S3.

SAA-C03 Question 4 of 7

Which storage should be used for the operating-system boot volume of an EC2 instance?

Answer: A — An Amazon EBS volume.

An EBS volume is a block device that serves as the persistent boot (root) volume for an EC2 instance. Why not the others: S3 is object storage and cannot be a bootable block device. EFS is a shared file system for data, not a boot volume. FSx for Lustre is a high-performance file system for compute workloads such as HPC and machine learning, not an OS boot disk. The instance's root device is EBS.

SAA-C03 Question 5 of 7

A data-processing job streams very large files sequentially and needs the lowest cost per gigabyte for high-throughput sequential access, on a volume attached to one instance. Which EBS volume type fits best?

Answer: A — Throughput Optimized HDD (st1).

Throughput Optimized HDD (st1) is designed for large, sequential, throughput-heavy workloads like log processing and big-data streaming at a low cost per gigabyte. Why not the others: Provisioned IOPS SSD (io2) targets high random IOPS for transactional databases at a premium price, not sequential throughput economy. gp3 is a balanced general-purpose SSD, fine but not the throughput-per-dollar leader for large sequential reads. Cold HDD (sc1) is for infrequently accessed data, so it does not suit a frequently running throughput job. Sequential throughput on a budget is st1.

SAA-C03 Question 6 of 7

A Windows-based application requires a shared file system accessible over the SMB protocol with Windows-native features such as Active Directory integration. Which service should a solutions architect choose?

Answer: A — Amazon FSx for Windows File Server.

Amazon FSx for Windows File Server provides a fully managed shared file system over SMB with native Windows features including Active Directory integration — the purpose-built fit. Why not the others: EFS uses NFS and targets Linux, so it does not natively serve SMB with Windows features. EBS Multi-Attach shares a block volume among a few instances in one AZ, not a Windows file share. An S3 file gateway is a hybrid on-premises bridge, not a native SMB file system for cloud instances. Windows SMB shares mean FSx for Windows File Server.

SAA-C03 Question 7 of 7

A batch job writes temporary scratch data that can be safely lost if the instance stops, and wants the highest possible local I/O performance at no additional storage cost. Which option fits?

Answer: A — An EC2 instance store (ephemeral) volume.

An instance store is physically attached local storage that offers very high I/O performance at no extra charge, and its data is ephemeral — lost when the instance stops or terminates, which is fine for disposable scratch data. Why not the others: a Provisioned IOPS EBS volume is durable and performant but costs more and is unnecessary for data you are happy to lose. EFS and S3 are network storage with more overhead than local scratch needs. Disposable, highest-local-performance scratch is the instance store.

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Frequently asked questions

How do I decide between block, object and file storage?

Match the access pattern. Block (EBS) attaches to one instance for boot volumes and databases. File (EFS for Linux/NFS, FSx for Windows/SMB or Lustre) is a shared POSIX file system many instances mount. Object (S3) is reached over an HTTP API for unlimited, durable files. The word 'shared', 'boot', 'database' or 'uploaded objects' usually settles it.

EFS or FSx — how do I tell them apart?

EFS is NFS and Linux-oriented. FSx for Windows File Server is SMB with Windows/Active Directory features; FSx for Lustre is high-performance computing. If the stem says Windows or SMB, it is FSx for Windows, not EFS.

Are these real exam questions?

No. They are original scenarios written for this page in the exam's style and difficulty. Reproducing real exam items violates the AWS certification agreement and can cost a candidate their certification — ours come with the reasoning attached instead.

What is the one-line takeaway?

One instance and low latency → EBS; many instances sharing files → EFS (Linux) or FSx (Windows); unlimited objects over HTTP → S3; disposable local speed → instance store.

Updated for SAA-C03 (July 2026). The sample questions above are our own work in the style of the exam — not real exam items. The exam itself is set and marked by the certification body.