- A
Use Amazon EFS instead of EBS or S3 for the shared file system.
Amazon EFS is the managed AWS file service built for shared POSIX-style file access from multiple instances. It supports concurrent read/write access from many EC2 hosts and is a better fit than EBS, which is attached to a single instance, or S3, which provides object storage rather than a native shared filesystem. For an application that expects standard filesystem semantics, EFS is the correct storage layer.
- B
Create EFS mount targets in every Availability Zone that hosts application instances.
Mount targets in each active Availability Zone provide local network entry points to the file system for instances in that AZ. This improves availability and avoids unnecessary cross-AZ traffic for file access. In a multi-AZ application, placing mount targets wherever the workload runs is the standard design for efficient and resilient EFS connectivity.
- C
Use a single EBS Multi-Attach volume mounted read/write by all instances across AZs.
Why wrong: EBS Multi-Attach is not a general-purpose multi-AZ shared filesystem for application servers. It has service limitations and is not the correct service for many instances requiring concurrent shared file access across AZs. EFS is the AWS-managed option designed for this use case.
- D
Store the files in S3 and mount them directly through the console as a shared network filesystem.
Why wrong: S3 is object storage, not a native shared filesystem with standard POSIX semantics. It does not provide the same low-latency metadata behavior or filesystem-level concurrent read/write model that application servers expect. This option does not satisfy the workload requirements.
- E
Place the files on instance store volumes so each server has faster local access.
Why wrong: Instance store is local to a single EC2 instance and is ephemeral. That means each server would have its own isolated copy of the data, which breaks the requirement for a shared filesystem across multiple instances. It also risks data loss if an instance stops or terminates.
Quick Answer
The answer is to create EFS mount targets in every Availability Zone that hosts application instances. Amazon EFS is the only AWS service that provides a fully managed, POSIX-compliant shared file system designed for concurrent read/write access from multiple EC2 instances across different AZs, with strong consistency and low-latency metadata operations that are critical when many application servers actively modify the same files. On the SAA-C03 exam, this scenario tests your ability to distinguish between shared storage services: EBS volumes are locked to a single AZ and cannot be shared, while S3 lacks POSIX semantics and fast metadata performance. A common trap is choosing EBS Multi-Attach, but that only works within a single AZ and has strict instance limits. Memory tip: think "EFS for Elastic File Sharing" — if your instances span AZs and need POSIX locking, EFS is the only fit.
SAA-C03 Design High-Performing Architectures Practice Question
This SAA-C03 practice question tests your understanding of design high-performing architectures. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 in different Availability Zones need concurrent read/write access to the same shared files. The files are actively modified by several application servers, and low-latency metadata operations matter more than extremely high aggregate throughput. Which two changes should the team make? Select two.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Use Amazon EFS instead of EBS or S3 for the shared file system.
Amazon EFS provides a fully managed, POSIX-compliant, shared file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones (AZs). It supports concurrent read/write access with strong consistency, and its metadata operations are optimized for low latency, making it ideal for workloads where many application servers actively modify the same files. EBS cannot be shared across AZs, and S3 lacks POSIX semantics and low-latency metadata operations.
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.
- ✓
Use Amazon EFS instead of EBS or S3 for the shared file system.
Why this is correct
Amazon EFS is the managed AWS file service built for shared POSIX-style file access from multiple instances. It supports concurrent read/write access from many EC2 hosts and is a better fit than EBS, which is attached to a single instance, or S3, which provides object storage rather than a native shared filesystem. For an application that expects standard filesystem semantics, EFS is the correct storage layer.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Create EFS mount targets in every Availability Zone that hosts application instances.
Why this is correct
Mount targets in each active Availability Zone provide local network entry points to the file system for instances in that AZ. This improves availability and avoids unnecessary cross-AZ traffic for file access. In a multi-AZ application, placing mount targets wherever the workload runs is the standard design for efficient and resilient EFS connectivity.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a single EBS Multi-Attach volume mounted read/write by all instances across AZs.
Why it's wrong here
EBS Multi-Attach is not a general-purpose multi-AZ shared filesystem for application servers. It has service limitations and is not the correct service for many instances requiring concurrent shared file access across AZs. EFS is the AWS-managed option designed for this use case.
- ✗
Store the files in S3 and mount them directly through the console as a shared network filesystem.
Why it's wrong here
S3 is object storage, not a native shared filesystem with standard POSIX semantics. It does not provide the same low-latency metadata behavior or filesystem-level concurrent read/write model that application servers expect. This option does not satisfy the workload requirements.
- ✗
Place the files on instance store volumes so each server has faster local access.
Why it's wrong here
Instance store is local to a single EC2 instance and is ephemeral. That means each server would have its own isolated copy of the data, which breaks the requirement for a shared filesystem across multiple instances. It also risks data loss if an instance stops or terminates.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse EBS Multi-Attach with a cross-AZ shared storage solution, but Multi-Attach is strictly limited to a single AZ and a small number of instances, while EFS is the only AWS shared file system that natively spans AZs with concurrent read/write access.
Detailed technical explanation
How to think about this question
EFS uses the NFSv4.1 protocol, which supports file locking and strong consistency for concurrent writes. Under the hood, EFS distributes file data across multiple AZs within a region, and each mount target provides a highly available NFS endpoint. The low-latency metadata operations are achieved through a distributed metadata layer that avoids the overhead of object storage APIs, making EFS suitable for content management systems, web serving, or shared application configurations where many instances need to update the same files simultaneously.
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.
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FAQ
Questions learners often ask
What does this SAA-C03 question test?
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: Use Amazon EFS instead of EBS or S3 for the shared file system. — Amazon EFS provides a fully managed, POSIX-compliant, shared file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones (AZs). It supports concurrent read/write access with strong consistency, and its metadata operations are optimized for low latency, making it ideal for workloads where many application servers actively modify the same files. EBS cannot be shared across AZs, and S3 lacks POSIX semantics and low-latency metadata operations.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This SAA-C03 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SAA-C03 exam.
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