SAP-C02 Continuous Improvement for Existing Solutions Practice Question
A company is migrating an on-premises application to AWS. The application requires persistent shared storage that can be accessed by multiple EC2 instances simultaneously with strong consistency. Which AWS storage solution should the company use?
⚠ Common exam trap
The trap is confusing EBS Multi-Attach with a shared file system. EBS Multi-Attach allows multiple instances to attach the same volume, but it does not provide a clustered file system, so concurrent writes can lead to data corruption.
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 EFS
Amazon EFS is a fully managed, scalable, shared file storage service for EC2 instances. It provides strong consistency and supports simultaneous access from multiple EC2 instances across multiple Availability Zones. It is designed for applications that require shared storage, making it the correct choice. The other options do not provide persistent shared storage with strong consistency for multiple instances.
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 S3 with S3 File Gateway.
Why it's wrong here
S3 File Gateway presents file shares backed by S3 objects, adding caching and gateway dependency rather than providing a native POSIX shared file system with strong consistency across EC2 instances. It suits hybrid file-to-object tiering, not concurrent multi-instance shared storage; Amazon EFS or FSx fits that requirement.
- ✗
Amazon S3 Glacier Deep Archive.
Why it's wrong here
S3 Glacier Deep Archive is an archival object store with retrieval times measured in hours and no POSIX file semantics, so it cannot present a concurrently mounted, strongly consistent file system. It suits long-term compliance archives, not shared storage for running EC2 instances.
- ✗
Amazon EBS with Multi-Attach enabled.
Why it's wrong here
Amazon EBS with Multi-Attach allows a single EBS volume to be attached to multiple instances, but it is block-level storage and requires a cluster-aware file system; it is not a fully managed shared file system.
- ✓
Amazon EFS
Why this is correct
Amazon EFS provides a shared, POSIX-compliant NFS file system mountable concurrently by many EC2 instances across Availability Zones, with strong read-after-write consistency. This satisfies the simultaneous multi-instance access and strong consistency constraints that single-attach EBS volumes cannot meet.
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 |
Go deeper
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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 Amazon Web Services exam blueprint
This SAP-C02 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 SAP-C02 exam.