Storage selection starts with the interface. S3 is object storage accessed by API. EBS is block storage attached within an AZ. EFS is a regional shared POSIX file system. FSx supplies managed file systems for Windows, Lustre, ONTAP, or OpenZFS requirements.
| Signal in the question | Likely choice |
|---|---|
| Static assets, data lake, durable objects | S3 |
| Boot volume or low-latency block device | EBS |
| Shared Linux files across AZs | EFS |
| SMB/Windows integration | FSx for Windows |
| HPC scratch tightly integrated with S3 | FSx for Lustre |
| Temporary highest-speed local data | Instance Store |
S3 design is policy plus lifecycle
Versioning protects against overwrite and is required for replication. CRR crosses Regions; SRR stays in one Region. Lifecycle transitions objects according to access age; Intelligent-Tiering fits changing or unknown access patterns. Glacier choices trade retrieval time and cost.
SSE-S3 uses S3-managed keys; SSE-KMS adds KMS control and audit; SSE-C leaves key delivery to the client. Block Public Access is a guardrail, while bucket policies express resource access. OAC is the preferred way for CloudFront to access a private S3 origin.
Backup is not availability
EBS snapshots and S3 versioning help recovery, but do not create a live standby. EBS moves across AZs through snapshot/restore. AWS Backup centralizes policies and vault controls. Object Lock or Vault Lock addresses immutability requirements.
For hybrid transfer, DataSync moves online datasets, Storage Gateway exposes familiar file/volume/tape interfaces, Transfer Family provides managed SFTP/FTPS/FTP, and Snow Family handles constrained networks or edge processing.
Exam lens: identify interface, sharing scope, latency, durability, recovery time, and access frequency—in that order.
Review card
- S3 object, EBS block, EFS/FSx file.
- EBS is AZ-scoped; EFS is regional.
- Replication requires versioning and does not retroactively copy everything by default.
- Lifecycle is a cost policy, not a backup strategy.
- Select migration tools by network availability and required protocol.