CV0-004 Cloud Architecture and Design Practice Question
A cloud architect is designing a solution that requires a shared, POSIX-compliant file system that can be mounted concurrently by hundreds of Linux EC2 instances across multiple Availability Zones in the same AWS Region. The workload is read-heavy, and the file system must scale storage capacity automatically as data grows. Which AWS service should the architect choose?
⚠ Common exam trap
The trap here is assuming that Amazon EBS Multi-Attach provides a shared file system for multiple instances across Availability Zones, when it actually only supports block-level attachment within a single Availability Zone.
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
✓
Amazon Elastic File System (Amazon EFS)
Amazon EFS is the correct choice because it is a managed NFS file system that supports POSIX semantics, can be mounted by many Linux instances simultaneously across multiple Availability Zones, and elastically scales storage capacity. The other services either provide block storage, Windows-oriented SMB file storage, or hybrid gateway functionality that does not meet the cross-AZ shared file system requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Storage Gateway in File Gateway mode
Why it's wrong here
AWS Storage Gateway File Gateway presents an SMB or NFS file interface to on-premises applications and caches data to Amazon S3, but it is not a native, scalable file system for hundreds of EC2 instances. It is designed primarily for hybrid cloud access and does not provide the automatic scaling and cross-AZ concurrent mount capabilities required in this scenario.
- ✗
Amazon Elastic Block Store (Amazon EBS) with Multi-Attach enabled
Why it's wrong here
Amazon EBS Multi-Attach allows a single Provisioned IOPS volume to be attached to multiple Nitro-based instances in the same Availability Zone, but it does not support cross-AZ attachment and does not provide a POSIX file system. EBS is block storage, not a shared file system, so it cannot satisfy the requirement for hundreds of Linux instances across multiple Availability Zones.
- ✗
Amazon FSx for Windows File Server
Why it's wrong here
Amazon FSx for Windows File Server provides a fully managed Windows file system that supports the SMB protocol, not POSIX-compliant NFS. Although it can be accessed from Linux instances via SMB, it is not designed for native POSIX compliance and is typically used for Windows-based workloads. It would introduce unnecessary protocol translation and complexity for this Linux-centric scenario.
- ✓
Amazon Elastic File System (Amazon EFS)
Why this is correct
Amazon EFS is a fully managed, elastic NFS file system that supports the POSIX interface and can be mounted concurrently by thousands of EC2 instances across multiple Availability Zones within a Region. It automatically scales storage capacity up and down as files are added or removed, making it ideal for read-heavy shared workloads that require cross-AZ access.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.