AWS S3 vs EFS vs FSx – Storage Service Comparison

Overview

AWS offers multiple storage services designed for different workloads. Amazon S3 provides object storage accessed via API, Amazon EFS delivers managed NFS file storage, and the Amazon FSx family offers four purpose-built file systems (Lustre, Windows File Server, NetApp ONTAP, and OpenZFS). Choosing the right storage service depends on access patterns, performance requirements, protocol needs, and cost considerations.

Amazon S3 – Object Storage

• Amazon S3 is a highly durable object storage service with a simple key-value design for storing any amount of data.
• Accessed via REST API (PUT, GET, DELETE) — not a file system by default.
• Provides 11 9’s (99.999999999%) durability by replicating data across at least 3 AZs.
• Offers unlimited storage — stores over 500 trillion objects across hundreds of exabytes (as of 2026).
• Supports multiple storage classes: Standard, Intelligent-Tiering, Standard-IA, One Zone-IA, Express One Zone, Glacier Instant Retrieval, Glacier Flexible Retrieval, and Glacier Deep Archive.
• S3 Express One Zone provides single-digit millisecond latency with 10x faster access than S3 Standard.
• 🆕 S3 Files (April 2026) — enables mounting S3 buckets as NFS v4.2 file systems on EC2, Lambda, EKS, and ECS with ~1ms latency and POSIX semantics.
• 🆕 S3 Access Points for FSx — allows accessing FSx for NetApp ONTAP and FSx for OpenZFS data via the S3 API without copying data.
• Best for: data lakes, backups, static website hosting, archive, big data analytics, content distribution.

Amazon EFS – Elastic File System

• Amazon EFS is a fully managed, elastic NFS file system for Linux-based workloads.
• Accessed via NFS v4.0/v4.1 protocol — mount as a standard file system on EC2, ECS, EKS, Lambda, and on-premises servers.
• Provides Regional (Multi-AZ) durability by replicating data across multiple AZs, or One Zone for lower-cost single-AZ storage.
• Elastic scaling — grows and shrinks automatically with no provisioning required. Pay only for storage used.
• Supports up to 60 GiB/s read throughput, 2.5 million read IOPS, and 500,000 write IOPS (2024 enhancements).
• Three storage classes: EFS Standard ($0.30/GB-month, sub-ms latency), EFS Infrequent Access ($0.016/GB-month), and EFS Archive ($0.008/GB-month — up to 97% lower than Standard).
• Supports Lifecycle Management to automatically tier data between Standard, IA, and Archive based on access patterns.
• Supports up to 10,000 access points per file system for multi-tenant and containerized applications.
• Best for: shared home directories, CMS, development environments, containerized applications, machine learning training data.

Amazon FSx Family

FSx for Lustre

• Fully managed high-performance parallel file system based on open-source Lustre.
• Delivers sub-millisecond latency, up to 1,000 GB/s throughput, and millions of IOPS.
• Uses a custom POSIX-compliant protocol optimized for performance (Linux clients only).
• Native S3 integration via Data Repository Associations (DRA) — automatically imports/exports data between FSx and S3.
• Deployment types: Persistent (long-term storage with data replicated within AZ) and Scratch (temporary high-burst workloads, no replication).
• Storage options: SSD, HDD, and Intelligent-Tiering (elastic, starting at $0.004/GB-month for Archive tier).
• Best for: HPC, machine learning training, financial modeling, genomics, video rendering, EDA.

FSx for Windows File Server

• Fully managed Windows-native file system built on Windows Server with full SMB protocol support.
• Accessed via SMB 2.0/2.1/3.0/3.1.1 protocol — supports Windows, Linux, and macOS clients.
• Integrates with Microsoft Active Directory for authentication and Windows ACLs for access control.
• Supports Multi-AZ deployment for 99.99% availability with automatic failover.
• Up to 20 GB/s throughput and hundreds of thousands of IOPS per file system.
• Maximum file system size: 64 TiB.
• Supports DFS Namespaces, DFS Replication, shadow copies, user quotas, and data deduplication.
• Best for: Windows application workloads, home directories, .NET applications, SQL Server, SharePoint, IIS.

FSx for NetApp ONTAP

• Fully managed NetApp ONTAP file system providing enterprise-grade multi-protocol storage.
• Supports NFS, SMB, and iSCSI protocols simultaneously — the only FSx option with block storage (iSCSI).
• Up to 72-80 GB/s throughput and millions of IOPS with virtually unlimited storage (tens of PBs).
• Automatic storage tiering moves cold data to lower-cost capacity pool storage.
• Supports Multi-AZ deployment (99.99% SLA), snapshots, cloning, SnapMirror replication, and FlexCache.
• Integrates with Active Directory for SMB access and supports NFS ACLs.
• 🆕 S3 Access Points (2025) — access file data stored in ONTAP volumes via the S3 API for AI/analytics workloads without data movement.
• Best for: enterprise NAS migration, multi-protocol workloads, Oracle/SAP, DevOps (cloning), hybrid cloud.

FSx for OpenZFS

• Fully managed OpenZFS file system optimized for low-latency workloads.
• Accessed via NFS v3/v4.0/v4.1/v4.2 — supports Linux, Windows, and macOS clients.
• Delivers sub-0.5ms latency, up to 21 GB/s throughput (cached) / 10 GB/s (disk), and up to 2 million IOPS.
• Maximum file system size: 512 TiB.
• Supports instant snapshots, data cloning (space-efficient copies), and point-in-time recovery.
• Supports Multi-AZ deployment (99.99% SLA) and Single-AZ (99.5% SLA).
• 🆕 S3 Access Points (June 2025) — access OpenZFS file data via S3 API.
• Best for: development/test (fast cloning), Linux workloads migrating from on-premises ZFS, databases, CI/CD pipelines.

Access Patterns Comparison

Performance Tiers Comparison

Pricing Model Comparison

Key Pricing Insights:

• S3 is the cheapest for raw storage ($0.023/GB) but charges per API request — ideal for infrequent access or bulk data.
• EFS is the most expensive per GB ($0.30) but offers elastic scaling with no provisioning — use Lifecycle policies to move data to IA/Archive for savings.
• FSx for Lustre Intelligent-Tiering starts at $0.004/GB-month for archive data — lowest-cost managed Lustre option.
• FSx for NetApp ONTAP automatic tiering to capacity pool ($0.0125/GB) provides significant savings for mixed workloads.
• FSx for Windows HDD at $0.013/GB-month is cost-effective for large Windows file shares with infrequent access.

Durability and Availability

Encryption

Access Control

Use Cases – When to Use Which

EFS vs EBS Multi-Attach

Both EFS and EBS Multi-Attach provide shared storage across multiple EC2 instances, but they are fundamentally different:

Exam Tip: Choose EFS when you need a simple shared file system across multiple instances and AZs. Choose EBS Multi-Attach only for specialized clustered applications (Oracle RAC, clustered databases) that require block-level access with application-managed I/O coordination within a single AZ.

FSx for Lustre with S3 Integration

FSx for Lustre provides native, bi-directional integration with Amazon S3 through Data Repository Associations (DRA):

• Automatic Import: When a client accesses a file, FSx for Lustre automatically imports the file metadata (and optionally data) from the linked S3 bucket. New/changed objects in S3 are automatically reflected in the file system.
• Automatic Export: New or modified files in the FSx file system are automatically exported back to the linked S3 bucket, keeping S3 as the durable long-term store.
• Lazy Loading: Only metadata is loaded initially; actual file data is fetched from S3 on first access (lazy load) or can be preloaded using hsm_restore.
• Data Tiering: With Intelligent-Tiering storage class, infrequently accessed data is automatically tiered to S3 (IA and Archive tiers) while maintaining file system visibility.
• Multiple DRAs: A single file system can be linked to multiple S3 buckets/prefixes, enabling consolidated access to distributed datasets.
• Cross-Account Access: FSx for Lustre can be linked to S3 buckets in different AWS accounts for shared data access.

Architecture Pattern — HPC/ML with S3 Data Lake:

• Store raw data durably in S3 (lowest cost, 11 9’s durability).
• Create a FSx for Lustre file system linked to the S3 bucket via DRA.
• Compute instances mount FSx for Lustre and process data at hundreds of GB/s throughput.
• Results are automatically exported back to S3.
• Delete the FSx file system after processing to save costs (scratch deployments).

Exam Tip: When a question mentions HPC or ML workloads that need to process data stored in S3 with high throughput and POSIX file system access, FSx for Lustre with DRA is the answer. FSx for Lustre acts as a high-speed processing layer on top of S3.

Detailed Comparison Table – All Storage Types

AWS Certification Exam Relevance

• SAA-C03 (Solutions Architect Associate): Frequently tests storage service selection based on access patterns, performance needs, cost optimization, and durability requirements. Know when to choose S3 vs EFS vs FSx.
• SAP-C02 (Solutions Architect Professional): Tests complex architectures combining S3 data lakes with FSx for Lustre processing, hybrid storage with ONTAP, and multi-protocol requirements.
• DEA-C01 (Data Engineer Associate): Tests FSx for Lustre with S3 integration for ETL pipelines, data lake architectures, and high-performance analytics.
• Key Exam Themes:
  • S3 = object storage, unlimited, cheapest, API access, data lake.
  • EFS = shared NFS file system, elastic, Linux, multi-AZ, POSIX.
  • FSx for Lustre = HPC, ML, highest throughput, S3 integration, Linux only.
  • FSx for Windows = Windows workloads, SMB, Active Directory, NTFS ACLs.
  • FSx for NetApp ONTAP = multi-protocol (NFS+SMB+iSCSI), enterprise NAS, auto-tiering.
  • FSx for OpenZFS = lowest latency, instant clones, dev/test, Linux NFS migration.
  • EBS Multi-Attach ≠ EFS — block vs file, single-AZ vs multi-AZ, requires cluster-aware FS.

AWS Certification Exam Practice Questions

• Questions are collected from Internet and the answers are marked as per my knowledge and understanding (which might differ with yours).
• AWS services are updated everyday and both the answers and questions might be outdated soon, so research accordingly.
• AWS exam questions are not updated to keep up the pace with AWS updates, so even if the underlying feature has changed the question might not be updated
• Open to further feedback, discussion and correction.

1. A genomics research company stores 500 TB of sequencing data in Amazon S3. Their HPC cluster needs to process this data with sub-millisecond latency and hundreds of GB/s throughput using a POSIX-compliant file system. The processed results must be stored back in S3 for long-term retention. Which solution meets these requirements with MINIMUM operational overhead?
   1. Copy data from S3 to Amazon EFS, process on EC2, copy results back to S3
   2. Create an FSx for Lustre file system with a Data Repository Association linked to the S3 bucket
   3. Mount S3 using S3 Files on the HPC cluster instances
   4. Use AWS DataSync to copy data from S3 to FSx for OpenZFS

   Answer: b. FSx for Lustre provides native S3 integration via Data Repository Associations, delivering sub-ms latency and up to 1,000 GB/s throughput. Data is automatically imported from and exported back to S3 without manual copy operations.

2. A company is migrating an on-premises Windows file server to AWS. The application requires SMB protocol access, Active Directory authentication, Windows ACLs, DFS Namespaces, and shadow copies for end-user file restore. Which AWS storage service should they use?
   1. Amazon EFS with Windows clients
   2. Amazon S3 with AWS Transfer Family
   3. Amazon FSx for Windows File Server
   4. Amazon FSx for NetApp ONTAP with SMB

   Answer: c. FSx for Windows File Server is purpose-built for Windows workloads with native SMB support, Active Directory integration, NTFS ACLs, DFS Namespaces, DFS Replication, and shadow copies. While FSx for NetApp ONTAP also supports SMB, it doesn’t provide native DFS Namespaces or Windows shadow copies.

3. A media company needs shared file storage accessible from both Linux-based video rendering instances (using NFS) and Windows-based editing workstations (using SMB) simultaneously. They also need automatic tiering of cold data to lower-cost storage. Which solution provides this capability with a SINGLE file system?
   1. Amazon EFS with SMB gateway
   2. Amazon FSx for Windows File Server with NFS
   3. Amazon S3 with Transfer Family for NFS and SMB
   4. Amazon FSx for NetApp ONTAP

   Answer: d. FSx for NetApp ONTAP is the only AWS file service that supports NFS, SMB, and iSCSI simultaneously on the same file system, with automatic storage tiering that moves cold data to a lower-cost capacity pool.
4. A development team wants to create multiple test environments by cloning a 10 TB production database file system. They need the clones to be created instantly without consuming additional storage for unchanged data. The file system uses NFS protocol on Linux. Which AWS service provides this capability MOST cost-effectively?
   1. Amazon EFS with AWS Backup restore
   2. Amazon FSx for Lustre with multiple file systems
   3. Amazon FSx for OpenZFS with instant cloning
   4. Amazon EBS snapshots with volume restore

   Answer: c. FSx for OpenZFS supports instant, space-efficient cloning using copy-on-write. Clones are created instantly regardless of data size and consume no additional storage for unchanged data. This is ideal for development/test environments.

5. A solutions architect needs to choose a storage solution for a containerized application running on Amazon EKS. The application requires shared persistent storage across multiple pods in different Availability Zones, POSIX file permissions, and automatic scaling without capacity planning. Which storage service is MOST appropriate?
   1. Amazon EBS with CSI driver
   2. Amazon S3 with CSI driver
   3. Amazon EFS with EFS CSI driver
   4. Amazon FSx for Lustre with CSI driver

   Answer: c. Amazon EFS provides multi-AZ shared file storage with POSIX permissions and elastic scaling (no capacity planning needed). The EFS CSI driver enables EKS pods to mount EFS as persistent volumes. EBS is single-AZ and cannot be shared across AZs; S3 is not a file system; FSx for Lustre requires capacity provisioning.

6. A company has a data pipeline where raw data lands in S3, needs high-performance file processing, and the results are used by AI services through the S3 API. They currently copy data between S3 and their file system, creating data duplication. Which AWS feature eliminates this data movement while allowing both file and S3 API access to the SAME data? (Select TWO)
   1. S3 Object Lambda
   2. FSx for Lustre Data Repository Association
   3. AWS DataSync with S3 as destination
   4. S3 Access Points for FSx for NetApp ONTAP
   5. S3 Transfer Acceleration

   Answer: b, d. FSx for Lustre DRA provides automatic bi-directional sync between the file system and S3. S3 Access Points for FSx for NetApp ONTAP allow accessing file data stored in ONTAP volumes directly via the S3 API without copying data, enabling AI/analytics services to work with file data natively.
7. An organization needs to store compliance data for 7 years with the lowest possible storage cost. The data is written once and rarely accessed (less than once per year). Retrieval time of 12 hours is acceptable. Which storage option provides the LOWEST cost?
   1. Amazon EFS Archive storage class
   2. Amazon S3 Glacier Flexible Retrieval
   3. Amazon S3 Glacier Deep Archive
   4. Amazon FSx for Lustre Intelligent-Tiering Archive tier

   Answer: c. S3 Glacier Deep Archive is the lowest-cost storage in AWS at $0.00099/GB-month (~$1/TB/month) with 12-48 hour retrieval time, specifically designed for data retained 7+ years with rare access. EFS Archive ($0.008/GB) is 8x more expensive.

Related Posts

• AWS S3 vs EBS vs EFS
• AWS EFS vs EBS Multi-Attach
• AWS Elastic File Store – EFS
• AWS FSx for Lustre
• AWS FSx for Windows File Server
• AWS S3 Security
• AWS S3 Encryption
• AWS Storage & Content Delivery – Cheat Sheet

References

• Choosing an Amazon FSx File System
• When to Choose Amazon EFS
• Amazon S3 Overview
• Amazon EFS Pricing
• Amazon FSx for Lustre Pricing
• Amazon FSx for Windows File Server Pricing
• Amazon FSx for NetApp ONTAP Pricing
• Amazon FSx for OpenZFS Pricing
• S3 Access Points for Amazon FSx
• FSx for Lustre Data Repository Associations