SAA-C03 Design High-Performing Architectures Practice Question
Exhibit
Deployment notes for a media-processing Auto Scaling group: - 6 EC2 instances across 2 Availability Zones - Each node compiles project artifacts and writes them to /workspace/output - Other nodes must immediately see the same files for the next pipeline stage - Files must persist when an instance is replaced or scaled in/out - Logs show failures such as: [ERROR] missing artifact: /workspace/output/frame_2048.png [WARN] local copy not found after instance termination
Based on the exhibit, which storage design best supports the application servers' shared working directory requirement?
⚠ Common exam trap
Test-takers frequently confuse object storage (S3) with shared file storage, assuming S3 can serve as a drop-in replacement for a POSIX filesystem, but S3 lacks file locking, atomic renames, and low-latency metadata operations required for a shared working directory.
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
✓
Mount Amazon EFS on every EC2 instance and use it as the shared workspace.
Amazon EFS provides a fully managed, NFS-based shared file system that can be mounted concurrently on multiple EC2 instances across multiple Availability Zones. This directly satisfies the requirement for a shared working directory where all application servers can read and write files simultaneously without additional synchronization overhead.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Mount Amazon EFS on every EC2 instance and use it as the shared workspace.
Why this is correct
EFS provides shared, persistent, POSIX-compliant file access across multiple EC2 instances and Availability Zones. That matches the requirement that all nodes see the same workspace immediately and that files survive instance replacement. It is the right choice when the application needs a common filesystem rather than an object store or local-only disk.
- ✗
Attach one gp3 EBS volume to each instance and synchronize the files with cron jobs.
Why it's wrong here
Separate EBS volumes are local to each instance, so they do not provide a shared workspace or immediate consistency across nodes.
When this WOULD be correct
This option would be correct if the requirement was for each instance to have its own independent working directory with periodic backups or synchronization for disaster recovery, not a shared real-time workspace.
- ✗
Store the artifacts in S3 and have each node read them directly from S3 as a filesystem.
Why it's wrong here
S3 is object storage, not a shared POSIX filesystem, so it does not satisfy the low-latency shared directory requirement.
When this WOULD be correct
When the application servers need to read static artifacts (e.g., configuration files, binaries) that are rarely updated, and the design prioritizes cost savings over low-latency file operations, S3 with direct reads (e.g., via SDK) would be a correct choice.
- ✗
Use instance store on each instance because it provides the fastest local file access.
Why it's wrong here
Instance store is fast, but it is ephemeral and local to one machine, so other nodes cannot share it and replacements lose data.
When this WOULD be correct
For a scenario requiring the highest I/O performance for temporary, non-persistent data that is unique to each instance (e.g., scratch space for large-scale data processing), where data loss on instance stop is acceptable.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The SAA-C03 exam frequently reuses these exact scenarios with slightly different constraints.
✓Mount Amazon EFS on every EC2 instance and use it as the shared workspace.Correct answer▾
Why this is correct
EFS provides shared, persistent, POSIX-compliant file access across multiple EC2 instances and Availability Zones. That matches the requirement that all nodes see the same workspace immediately and that files survive instance replacement. It is the right choice when the application needs a common filesystem rather than an object store or local-only disk.
✗Attach one gp3 EBS volume to each instance and synchronize the files with cron jobs.Wrong answer — click to see why▾
Why this is wrong here
Synchronizing files with cron jobs introduces latency and inconsistency, failing to provide a real-time shared working directory as required by the application servers.
★ When this WOULD be the correct answer
This option would be correct if the requirement was for each instance to have its own independent working directory with periodic backups or synchronization for disaster recovery, not a shared real-time workspace.
Why candidates choose this
Candidates may think that using EBS volumes with cron-based sync is a cost-effective way to achieve file sharing, underestimating the complexity and inconsistency of distributed synchronization.
✗Store the artifacts in S3 and have each node read them directly from S3 as a filesystem.Wrong answer — click to see why▾
Why this is wrong here
Using S3 as a filesystem (e.g., via s3fs) introduces latency and consistency issues that are unsuitable for a shared working directory requiring low-latency, POSIX-compliant file operations across multiple EC2 instances.
★ When this WOULD be the correct answer
When the application servers need to read static artifacts (e.g., configuration files, binaries) that are rarely updated, and the design prioritizes cost savings over low-latency file operations, S3 with direct reads (e.g., via SDK) would be a correct choice.
Why candidates choose this
Candidates may think S3 is a universal storage solution and overlook its lack of POSIX semantics and higher latency compared to EFS, especially when the question mentions 'shared working directory' which implies frequent, concurrent file operations.
✗Use instance store on each instance because it provides the fastest local file access.Wrong answer — click to see why▾
Why this is wrong here
Instance store provides temporary, block-level storage that is physically attached to the host, but data is lost if the instance is stopped or terminated. It cannot serve as a persistent shared working directory across multiple EC2 instances.
★ When this WOULD be the correct answer
For a scenario requiring the highest I/O performance for temporary, non-persistent data that is unique to each instance (e.g., scratch space for large-scale data processing), where data loss on instance stop is acceptable.
Why candidates choose this
Candidates may assume that the fastest local storage (instance store) is always the best choice, overlooking the requirement for persistence and sharing across instances.
Analysis generated from the official SAA-C03blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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