SAA-C03 Design Resilient Architectures Practice Question
A warehouse integration service must use shared file storage across Linux EC2 instances in multiple Availability Zones. The storage must remain available during an AZ failure. Which service should be used? The design must avoid adding custom operational scripts.
⚠ Common exam trap
A common mix-up: candidates confuse EBS Multi-Attach (which has strict limitations and requires cluster-aware file systems) with a true shared file system, or assume that S3 with a FUSE mount is a viable POSIX alternative without considering the operational overhead and lack of native consistency.
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 with mount targets in multiple Availability Zones
Amazon EFS provides a fully managed, POSIX-compliant NFSv4.1 shared file system that can be mounted concurrently across multiple Linux EC2 instances. By deploying mount targets in multiple Availability Zones, the file system remains accessible even if one AZ fails, satisfying the high-availability requirement without any custom scripts.
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 with mount targets in multiple Availability Zones
Why this is correct
EFS mount targets in multiple Availability Zones give each Linux instance a local endpoint, so file storage stays reachable if one AZ fails. EBS cannot attach across AZs, and the multi-AZ design needs no custom scripts.
- ✗
S3 mounted as a POSIX file system without a file gateway
Why it's wrong here
Mounting S3 without a file gateway requires third-party FUSE tooling and custom scripts, and it does not provide POSIX semantics or shared multi-AZ file locking. It is tempting because S3 is durable and region-wide, which suits object storage accessed through APIs or SDKs rather than mounted file systems.
- ✗
Instance store volumes
Why it's wrong here
Instance store volumes are physically attached to a single host, so data is lost if that host or its Availability Zone fails and cannot be shared between instances. It is tempting because instance store offers very high IOPS at no extra cost, which suits temporary buffers, caches or scratch data.
- ✗
An EBS volume attached to all instances
Why it's wrong here
An EBS volume is a block device that attaches to one instance in one Availability Zone; multi-attach is limited to io1/io2 within a single AZ and requires a cluster-aware file system, so it cannot span AZs. It is tempting because EBS is the default EC2 disk, which suits single-instance boot or data volumes.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.