AWS Cloud Practitioner Exam Guide: Mastering Storage and Compute Nuances

EBS vs EFS vs S3 — How Does Your App See the Storage?

The AWS Cloud Practitioner exam tests critical distinctions between block, file, and object storage architectures. Misconfiguring these services can lead to total data loss, as seen with the ephemeral Instance Store disks.

Why This Matters

Engineers must balance performance requirements against data persistence realities; for instance, while Instance Store offers the lowest latency by bypassing the network, it is non-persistent storage that vanishes upon instance termination. Understanding the trade-offs between Reserved pricing (72% discount) and Dedicated hardware (compliance-focused) is essential for aligning infrastructure with both budget and regulatory constraints.

Key Insights

• EBS provides block-level storage for single EC2 instances within a single Availability Zone, acting as a virtual hard drive.
• S3 functions as a globally accessible object store using API calls (PUT/GET) rather than traditional mounting, offering massive scale.
• AWS Backup centralizes automated backup policies across multiple AWS services and on-premises environments.
• Snowball Edge facilitates physical data transfer for terabyte-to-petabyte scale migrations when network bandwidth is impractical.
• Dedicated Hosts provide visibility into physical sockets and cores, enabling Bring Your Own License (BYOL) for server-bound software.

Practical Applications

• Use Case: Shared configuration files across multiple EC2 instances using EFS. Pitfall: Using EBS for shared access, which is limited to a single instance/AZ.
• Use Case: High-performance, fault-tolerant distributed architectures using Instance Store for temporary scratch space. Pitfall: Storing critical, non-replicated data on Instance Store resulting in permanent loss after hardware failure.
• Use Case: Hybrid storage integration via Storage Gateway to replace physical tape backups with S3/Glacier. Pitfall: Confusing Elastic Disaster Recovery with periodic backups, leading to inadequate point-in-time recovery options.

References:

• https://dev.to/c_claven_03c4a41605f86c8e4/aws-cloud-practitioner-exam-the-difficult-parts-part-3-storage-and-some-compute-4ff8