The answer is Amazon EFS, as it is the only AWS storage service that provides a fully managed, shared file system for EC2 across AZs using NFS. EFS uses the NFSv4.1 protocol and is POSIX-compliant, allowing multiple EC2 instances in different Availability Zones to concurrently read and write the same files, such as user uploads or rendered assets, without any additional configuration. On the SAA-C03 exam, this question tests your ability to distinguish between block, object, and file storage for multi-AZ shared access—a common trap is choosing EBS Multi-Attach, which only works within a single Availability Zone and does not support NFS. Remember that EFS is the go-to for any scenario requiring a shared NFS filesystem across AZs. A simple memory tip: EFS = Elastic File System, think “Everywhere File System” because it works across all AZs in a region.
SAA-C03 Design High-Performing Architectures Practice Question
This SAA-C03 practice question tests your understanding of design high-performing architectures. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Multiple EC2 instances need a shared filesystem so they can concurrently read and write the same files (for example, user uploads and rendered assets). The instances are in different Availability Zones and must mount the filesystem using NFS. Which AWS storage service best fits?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Amazon EFS
Amazon EFS is a fully managed NFS file system that supports concurrent read/write access from multiple EC2 instances across different Availability Zones. It uses the NFSv4.1 protocol, making it the only AWS storage service that provides a shared POSIX-compliant filesystem mountable via NFS for multi-AZ workloads.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Amazon EFS
Why this is correct
EFS provides a shared, NFS-compatible filesystem that supports mounting from multiple EC2 instances and AZs.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Amazon S3
Why it's wrong here
S3 is object storage and does not provide native shared POSIX/NFS filesystem semantics for concurrent writes.
✗
Amazon EBS gp3 volumes
Why it's wrong here
EBS volumes are tied to a single Availability Zone and cannot be mounted as a shared filesystem across AZs.
✗
Instance store on EC2
Why it's wrong here
Instance store is ephemeral and not suitable for a shared, concurrently written filesystem requirement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse Amazon S3's eventual consistency and HTTP-based access with a true shared filesystem, or assume EBS multi-attach (which is limited to a few instances in the same AZ) can replace a multi-AZ NFS solution.
Detailed technical explanation
How to think about this question
EFS uses a distributed data store with a file system interface that automatically scales storage capacity as files are added or removed. Under the hood, EFS leverages the NFSv4.1 protocol with support for file locking and strong read-after-write consistency, enabling multiple EC2 instances across different AZs to concurrently read and write the same files without data corruption. A real-world scenario is a web application where user-uploaded images are stored on EFS and processed by multiple EC2 instances running a rendering pipeline, ensuring all instances see the latest files immediately.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design High-Performing Architectures — This question tests Design High-Performing Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Amazon EFS — Amazon EFS is a fully managed NFS file system that supports concurrent read/write access from multiple EC2 instances across different Availability Zones. It uses the NFSv4.1 protocol, making it the only AWS storage service that provides a shared POSIX-compliant filesystem mountable via NFS for multi-AZ workloads.
What should I do if I get this SAA-C03 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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