Study guide
Technical reference and lesson notes
Purpose of This Lesson
AWS storage services are designed around different access models. This lesson introduces the distinction between block storage and file storage, and places four AWS services in that context:
- Amazon Elastic Block Store (EBS) for block volumes attached to Amazon EC2.
- Amazon Elastic File System (EFS) for shared file storage that multiple EC2 instances can access.
- Amazon FSx for managed file systems, including Microsoft Windows-compatible file systems.
- AWS Storage Gateway for integrating on-premises environments with AWS storage.
Understanding the access model is a foundational architecture decision. The correct service depends on how applications access data, whether data must be shared, and whether workloads run in AWS, on premises, or across both environments.
Key Concepts
Block Storage
Block storage presents raw storage volumes to a compute instance. The operating system formats the volume with a file system, and the instance manages files and directories on that volume.
Amazon EBS is AWS’s primary block storage service for EC2. A volume is attached to an EC2 instance and is commonly used for:
- Operating system disks
- Application data volumes
- Databases and other workloads requiring block-level access
Block storage is generally associated with a specific compute instance rather than being a shared file system for many instances.
File Storage
File storage presents a file system with familiar directories, file names, and permissions. Applications access files through a file-system protocol rather than treating the storage as an unformatted block device.
Amazon EFS provides a shared file system that can be mounted by multiple EC2 instances. This is useful when instances need concurrent access to the same files, such as shared application content or common configuration and data files.
Amazon FSx provides managed file-system options for workloads with specific compatibility or feature requirements. A key exam-relevant example is a Microsoft Windows-compatible file system for Windows servers and desktop-oriented workloads.
Hybrid Storage
AWS Storage Gateway connects on-premises environments to AWS storage services. It is intended for hybrid architectures in which existing applications or infrastructure remain on premises while cloud storage is incorporated into the solution.
Storage Gateway is therefore different from EBS, EFS, and FSx in its primary role: it is an integration and access layer for hybrid storage rather than simply a storage volume or cloud file system.
Architecture Decision Guide
| Requirement | Likely service | Reasoning |
|---|---|---|
| An EC2 instance needs a volume presented as a disk | Amazon EBS | Provides block storage for EC2 instances |
| Multiple EC2 instances must access the same file system | Amazon EFS | Provides shared file-based access |
| A workload requires a managed file system with Windows compatibility | Amazon FSx | Supports file-system options designed for specific workload and compatibility needs |
| On-premises systems must use or integrate with AWS storage | AWS Storage Gateway | Provides a bridge between on-premises infrastructure and AWS storage |
| An application needs files and directories rather than a raw disk device | EFS or FSx | Select based on sharing, operating system, and file-system compatibility requirements |
Selection Questions
When evaluating a storage requirement, ask:
- Does the application require a raw block device or a mounted file system?
- Will one EC2 instance or multiple instances access the data?
- Does the workload require Windows-specific compatibility or another specialized file-system capability?
- Are the clients located in AWS, on premises, or in both environments?
- Is the storage service being used directly by a workload, or is it serving as a hybrid connectivity layer?
Exam-Relevant Takeaways
- EBS is block storage and is used as a disk-like volume for EC2.
- EFS is file storage designed for shared access from multiple EC2 instances.
- FSx is a family of managed file-system options, selected when a workload needs a particular file-system type or compatibility model.
- AWS Storage Gateway supports hybrid storage architectures, connecting on-premises environments with AWS storage.
- Do not choose a service solely because it stores data. First identify the required storage interface: object, block, or file.
- A requirement for shared files across multiple EC2 instances points toward a shared file system, not a conventional single-instance block volume.
Common Exam Traps
- Confusing EBS with EFS: EBS provides block devices for EC2; EFS provides a shared file system.
- Treating all file storage as interchangeable: EFS and FSx may support different operating-system, compatibility, and workload requirements.
- Using Storage Gateway as a general-purpose EC2 disk: Storage Gateway is primarily for on-premises-to-AWS integration.
- Ignoring workload location: A requirement involving existing on-premises servers may indicate Storage Gateway rather than a cloud-only storage service.
- Selecting storage before identifying the access pattern: The words “persistent storage” alone do not distinguish between EBS, EFS, FSx, or object storage.
Real-World Engineer Notes
- Document storage requirements in terms of access protocol, sharing model, client location, and operating-system compatibility.
- A migration design may use different services at different stages. For example, on-premises systems may need hybrid access during transition, while cloud-native workloads may use EBS, EFS, or FSx directly.
- Separate the question of where data is stored from how applications access it. The access model often determines the service more directly than capacity does.
- For a complete architecture decision, also validate performance, availability, backup, security, throughput, and cost requirements. These details determine the final configuration after the storage type has been selected.
Quick Reference Summary
- Amazon EBS: Block storage attached to EC2; presented as a disk or volume.
- Amazon EFS: Shared file storage that multiple EC2 instances can mount and use.
- Amazon FSx: Managed file-system choices for specialized requirements, including Windows compatibility.
- AWS Storage Gateway: Hybrid integration between on-premises infrastructure and AWS storage.
- Primary decision: Choose based on the required interface and access pattern—block, shared file, specialized file system, or hybrid connectivity.
Flashcards
- Q: What type of storage does Amazon EBS provide?
A: Block storage for Amazon EC2 instances.
- Q: What is the defining characteristic of block storage?
A: It presents raw volumes that the operating system can format and manage as disks.
- Q: Which service provides a shared file system for multiple EC2 instances?
A: Amazon EFS.
- Q: What type of interface does a file-storage service provide?
A: A file system with directories, files, and file-system permissions.
- Q: When should Amazon FSx be considered?
A: When a workload needs a managed file system with specific compatibility or file-system requirements.
- Q: Which AWS storage service is associated with Microsoft Windows-compatible file-system workloads?
A: Amazon FSx.
- Q: What is the primary role of AWS Storage Gateway?
A: Connecting on-premises environments with AWS storage in a hybrid architecture.
- Q: What is the first question to ask when selecting among storage services?
A: Whether the application needs block storage, file storage, object storage, or hybrid access.
Practice Questions
Question 1
An application runs on several EC2 instances. All instances must access the same directory structure and shared application files. Which service best matches this requirement?
- A. Amazon EBS
- B. Amazon EFS
- C. AWS Storage Gateway
- D. Amazon S3 Glacier
Correct answer: B. Amazon EFS
Explanation: EFS provides shared file-based storage that multiple EC2 instances can access. EBS is block storage and is not the general shared-file-system choice described here.
Question 2
A single EC2 instance requires a disk-like volume on which the operating system and application can create and manage a file system. Which service should be selected?
- A. Amazon EBS
- B. Amazon EFS
- C. AWS Storage Gateway
- D. Amazon FSx only because it is file-based
Correct answer: A. Amazon EBS
Explanation: EBS provides block volumes that are attached to EC2 and managed by the operating system as disks.
Question 3
A company wants existing on-premises servers to use storage hosted in AWS as part of a hybrid migration strategy. Which service is most directly intended for this integration?
- A. Amazon EBS
- B. Amazon EFS
- C. AWS Storage Gateway
- D. Amazon EC2 instance store
Correct answer: C. AWS Storage Gateway
Explanation: Storage Gateway provides a bridge between on-premises environments and AWS storage services. EBS and EFS are cloud storage services used directly by AWS workloads rather than the primary hybrid integration layer.
Question 4
A workload requires a managed file system with compatibility for Microsoft Windows servers. Which service category should the architect investigate first?
- A. Amazon EBS
- B. Amazon FSx
- C. Amazon S3 only
- D. AWS Storage Gateway only
Correct answer: B. Amazon FSx
Explanation: FSx includes managed file-system options designed for specific compatibility requirements, including Microsoft Windows-oriented workloads.