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CLF-C02 Study Notes: Task Statement 3.6 — Identify AWS Storage Services

1. Cloud Storage Fundamentals

Cloud storage allows you to store data using an AWS-managed service instead of purchasing and managing physical storage hardware.

Key benefits

  • On-demand capacity: Provision storage when needed.
  • Pay-as-you-go pricing: Pay for the storage and features you use.
  • Scalability: Increase or decrease storage capacity as requirements change.
  • Durability: Protection against data loss.
  • Availability: Data remains accessible when needed.
  • Security: Access control, encryption, monitoring, and compliance features.
  • Lifecycle management: Automatically move data to lower-cost storage tiers.
  • Global access: Applications and users can access data over the network, subject to permissions and network configuration.

Three main storage types

Storage type AWS examples Basic concept Typical use
Object storage Amazon S3 Stores complete objects with metadata Backups, media, data lakes, archives
File storage Amazon EFS, Amazon FSx Shared hierarchical file system Shared application files, home directories
Block storage Amazon EBS Raw storage blocks attached to a compute instance Boot volumes, databases, low-latency applications

2. Amazon S3 — Object Storage

Amazon Simple Storage Service, or Amazon S3, is AWS’s highly scalable object storage service.

Core concepts

  • Data is stored as objects.
  • Objects are stored in buckets.
  • An object can include:
  • Data
  • Metadata
  • A key, which identifies the object
  • Buckets are created in a specific AWS Region.
  • Bucket names must be globally unique across AWS.
  • An object can range from 0 bytes to 5 TB.
  • S3 is designed for extremely high durability and large-scale storage.
  • Multiple users or applications can access objects, subject to permissions.
  • S3 can replicate data across Availability Zones within a Region and can be configured for cross-Region replication.

Common S3 use cases

  • Backup and restore
  • Data lakes and analytics
  • Static website assets
  • Images, videos, and other media
  • Application logs
  • Long-term archives
  • Software distribution

S3 versioning

S3 Versioning keeps multiple versions of an object in a bucket.

It helps protect against:

  • Accidental object overwrites
  • Accidental object deletion
  • Unwanted changes to data

If an object is overwritten, the previous version can be restored.

Exam tip: If the question asks how to protect objects from accidental overwrite or deletion, look for S3 Versioning.

Versioning does not automatically prevent authorized users from deleting or changing objects. For stronger protection against deletion, S3 Object Lock and appropriate permissions may be used, but CLF-C02 questions commonly focus on versioning.

S3 access and security

S3 supports:

  • IAM policies
  • Bucket policies
  • Access control settings
  • Encryption
  • Access logging and monitoring
  • Object tags and metadata
  • S3 access points
  • Lifecycle policies
  • Versioning

A bucket is not automatically public. Access must be explicitly allowed, and AWS recommends avoiding public access unless required.

Regional considerations

An S3 bucket resides in a selected AWS Region. This can affect:

  • Data residency
  • Regulatory requirements
  • Latency
  • Pricing
  • Disaster recovery design

Exam tip: “Globally unique bucket name” does not mean that the bucket is globally replicated by default. The bucket exists in one Region unless replication is configured.

3. S3 Storage Classes

S3 storage classes provide different trade-offs between storage cost, retrieval cost, availability, and access time.

Storage class Best for
S3 Standard Frequently accessed data
S3 Intelligent-Tiering Data with unknown or changing access patterns
S3 Standard-IA Infrequently accessed data that must be retrieved quickly
S3 One Zone-IA Infrequently accessed, reproducible data where lower cost is important
S3 Glacier Instant Retrieval Archive data requiring immediate access
S3 Glacier Flexible Retrieval Archive data accessed occasionally, with retrieval from minutes to hours
S3 Glacier Deep Archive Lowest-cost long-term archives with retrieval generally within 12 hours

Important distinctions

  • Standard: Suitable for frequently accessed data.
  • Intelligent-Tiering: Automatically moves objects between access tiers based on changing access patterns.
  • Infrequent Access classes: Lower storage cost, but retrieval charges and minimum storage-duration considerations may apply.
  • One Zone-IA: Stored in one Availability Zone and is appropriate only when data can be recreated.
  • Glacier classes: Designed for archival data, not frequently accessed application data.
  • Glacier Deep Archive: Lowest-cost option for long-term retention when retrieval can take up to approximately 12 hours.

Exam trap: Do not select S3 Glacier Deep Archive if the data must be immediately available. Consider S3 Standard, Standard-IA, or Glacier Instant Retrieval depending on the requirements.

S3 Lifecycle Management

S3 Lifecycle policies can automatically:

  • Transition objects to cheaper storage classes
  • Expire or delete objects after a specified time
  • Support cost optimization for data with changing access patterns

Example:

  1. Store new logs in S3 Standard.
  2. Move logs to S3 Standard-IA after 30 days.
  3. Move logs to Glacier after 90 days.
  4. Delete them after the required retention period.

4. Amazon EFS — File Storage for Linux

Amazon Elastic File System, or Amazon EFS, is a managed, elastic file system.

Key characteristics

  • Provides shared file storage.
  • Uses a file system structure with directories and files.
  • Can be mounted by multiple compute instances at the same time.
  • Commonly used with Linux workloads.
  • Uses the NFS protocol.
  • Automatically scales as files are added or removed.
  • Stores data separately from EC2 instance storage.
  • Supports high availability and durability across Availability Zones.
  • Can be accessed by resources in a VPC.
  • Can support hybrid access using services such as:
  • AWS Direct Connect
  • AWS Site-to-Site VPN

Common use cases

  • Shared application files
  • Content repositories
  • Media storage
  • Development environments
  • User home directories
  • Web serving platforms requiring shared files

Exam keyword: Linux + shared file system = Amazon EFS

EFS lifecycle management can move less frequently accessed files to a lower-cost EFS storage class.

EFS versus S3

Requirement Appropriate service
Store objects such as images, backups, or videos Amazon S3
Shared file system mounted by multiple Linux instances Amazon EFS
Raw block storage attached to an EC2 instance Amazon EBS

Exam trap: S3 is not a traditional file system, and EFS is not object storage.

5. Amazon FSx — Managed File Systems

Amazon FSx provides managed file systems designed for specific workloads.

Amazon FSx for Windows File Server

FSx for Windows File Server provides a managed Windows file system.

Key characteristics

  • Designed for Windows workloads.
  • Uses the SMB protocol.
  • Supports Windows file shares.
  • Integrates with Microsoft Active Directory.
  • Supports Windows access control lists.
  • Can be accessed from AWS and on-premises environments.
  • Supports high performance and high availability.
  • Can be configured for Multi-AZ deployments.

Common use cases

  • Windows applications
  • Microsoft SQL Server workloads
  • Windows home directories
  • Enterprise file shares
  • Applications requiring SMB or Active Directory

Exam keyword: Windows + SMB + Active Directory = FSx for Windows File Server

Amazon FSx for Lustre

FSx for Lustre is a high-performance, parallel file system.

Key characteristics

  • Designed for Linux workloads.
  • Suitable for high-performance computing.
  • Provides high throughput and low latency.
  • Uses a parallel distributed file system.
  • Suitable for large-scale processing.

Common use cases

  • Machine learning
  • High-performance computing
  • Video processing
  • Financial modeling
  • Engineering and scientific simulations
  • Design automation

Exam keyword: Linux + high-performance computing or machine learning = FSx for Lustre

EFS versus FSx

Service Main operating environment or protocol Best suited for
Amazon EFS Linux, NFS Elastic shared file storage
FSx for Windows File Server Windows, SMB, Active Directory Windows file shares
FSx for Lustre Linux, parallel file system High-performance computing

6. Amazon EBS — Block Storage

Amazon Elastic Block Store, or Amazon EBS, provides persistent block storage volumes for Amazon EC2.

Key characteristics

  • Provides block-level storage.
  • Volumes are attached to EC2 instances.
  • The operating system sees an EBS volume as a block device.
  • A file system can be created on top of the block storage.
  • EBS volumes can be used as:
  • Boot volumes
  • Application data volumes
  • Database storage
  • EBS is separate from the physical host hardware.
  • EBS volumes are designed to persist independently from the underlying EC2 host.
  • EBS volumes are generally associated with a single Availability Zone.
  • EBS snapshots provide point-in-time backups.

Common use cases

  • EC2 boot volumes
  • Databases
  • Enterprise applications
  • Applications requiring low-latency block storage
  • Persistent application data

EBS volume types

Volume type Typical use case Boot volume?
General Purpose SSD (gp) Most workloads, development, testing, boot volumes Yes
Provisioned IOPS SSD (io) Critical applications requiring sustained high IOPS, such as large databases Yes
Throughput Optimized HDD (st) Frequently accessed, throughput-oriented workloads such as big data, data warehouses, and log processing No
Cold HDD (sc) Infrequently accessed, throughput-oriented data where low cost is important No

Exam tip: If a question asks for the recommended EBS volume type for most workloads and boot volumes, select General Purpose SSD.

EBS snapshots

EBS snapshots are point-in-time backups of EBS volumes.

They can be used to:

  • Back up volume data
  • Restore data
  • Create new EBS volumes
  • Support disaster recovery
  • Copy backups to another Region

Snapshots are stored in AWS-managed storage, rather than being kept as files on the EC2 instance.

7. Instance Store versus EBS

EC2 instances may use either instance store or EBS storage.

Feature Instance Store Amazon EBS
Storage type Local, directly attached storage Network-attached block storage
Persistence Temporary or ephemeral Persistent
Performance Very fast and low latency High performance, but network-based
Survives instance host failure? No Designed to persist separately from host
Typical use Temporary files, caches, scratch data Boot volumes and persistent application data
Backup support Must be handled by the application EBS snapshots

Instance Store

Instance store is physically attached to the EC2 host.

Data may be lost if:

  • The underlying host fails
  • The instance is stopped or terminated, depending on the instance type and operation
  • The instance is moved to another host

Ephemeral storage means temporary storage that should not be relied upon for persistent data.

Exam trap: Use instance store for temporary or cache data—not databases, boot data, or important persistent information.

EBS

EBS is network-attached and persistent. It is commonly used as the root or boot volume for EC2 instances.

Exam keyword:
- Temporary, very fast local storage → Instance Store
- Persistent EC2 block storage → EBS

8. AWS Storage Gateway

AWS Storage Gateway connects on-premises environments with AWS cloud storage.

It is useful for:

  • Extending on-premises storage into AWS
  • Migrating data to AWS
  • Backing up on-premises data to AWS
  • Supporting hybrid cloud architectures
  • Reducing the need to immediately replace existing storage systems

Storage Gateway is commonly deployed as a virtual appliance on-premises or in an appropriate AWS environment.

Storage Gateway types

File Gateway

  • Presents file shares to on-premises applications.
  • Uses protocols such as SMB and NFS.
  • Stores files as objects in Amazon S3.
  • Maintains a local cache for frequently accessed data.

Use when: Applications need file access locally, but the data should be stored in S3.

Volume Gateway

Provides block storage volumes to on-premises applications using iSCSI.

Stored Volumes

  • Primary data is stored on-premises.
  • Snapshots and backups are stored in AWS, typically in Amazon S3.
  • Useful when local access to the complete dataset is required.

Cached Volumes

  • Primary data is stored in AWS.
  • Frequently accessed data is cached on-premises.
  • Useful when reducing on-premises storage requirements is important.

Tape Gateway

  • Presents a virtual tape library to existing backup software.
  • Used for backup and archival workflows.
  • Stores virtual tapes in AWS storage.
  • Helps organizations migrate from physical tape systems without changing existing backup processes.

Storage Gateway comparison

Gateway type Local interface AWS storage destination Main use
File Gateway SMB/NFS file shares Amazon S3 File-based access with S3 storage
Volume Gateway iSCSI block volumes AWS-backed storage and snapshots Block storage for on-premises servers
Tape Gateway Virtual tape library AWS storage Backup and archival using tape-based software

Exam trap: Storage Gateway is not the same as AWS DataSync. Storage Gateway provides ongoing hybrid storage access, while DataSync is primarily used for online data transfer and synchronization.

9. AWS Backup

AWS Backup is a fully managed service for centralizing and automating backups.

Key characteristics

  • Creates centralized backup policies.
  • Automates backup schedules.
  • Supports monitoring of backup activity.
  • Helps meet compliance and retention requirements.
  • Reduces the need for service-specific scripts and manual processes.
  • Can protect supported AWS resources and some on-premises workloads.

Exam keyword:
Centralized, automated backup management across AWS services = AWS Backup

AWS Backup versus EBS snapshots

  • EBS snapshot: Backup of an individual EBS volume.
  • AWS Backup: Centralized backup management across supported AWS resources using policies and schedules.

10. Common Comparisons

S3 versus EFS versus EBS

Requirement Service
Object storage for backups, media, and data lakes Amazon S3
Shared file system for multiple Linux instances Amazon EFS
Windows file share using SMB and Active Directory Amazon FSx for Windows File Server
High-performance parallel file system for Linux FSx for Lustre
Persistent block storage for an EC2 instance Amazon EBS
Temporary, very fast local EC2 storage Instance Store
Hybrid access to S3 or AWS-backed storage from on premises AWS Storage Gateway
Centralized backups across AWS services AWS Backup

11. Exam Tips and Traps

  1. S3 is object storage.
    Do not choose S3 when the question requires a mounted file system or block device.

  2. EFS is primarily for Linux shared file storage.
    For Windows SMB file shares and Active Directory, choose FSx for Windows File Server.

  3. FSx for Lustre is for high-performance Linux workloads.
    Look for machine learning, HPC, video processing, or very high-throughput workloads.

  4. EBS is block storage for EC2.
    It is commonly used for boot volumes and persistent application data.

  5. Instance Store is ephemeral.
    Do not store data there if it must survive an instance or host failure.

  6. General Purpose SSD is the standard EBS answer for most workloads.
    Provisioned IOPS SSD is for applications requiring sustained, high IOPS performance.

  7. HDD EBS volumes cannot be used as boot volumes.

  8. S3 bucket names are globally unique.
    A bucket is still created in a specific Region.

  9. S3 Versioning protects against accidental overwrite and deletion.

  10. Use S3 Glacier Deep Archive for the lowest-cost long-term archive storage when retrieval within approximately 12 hours is acceptable.

  11. Use S3 Lifecycle policies to transition data automatically to lower-cost storage classes.

  12. AWS Backup centralizes backup management.
    It is not simply another name for an EBS snapshot.

  13. Storage Gateway supports hybrid storage.

    • File Gateway → S3 objects accessed through file shares
    • Volume Gateway → iSCSI block volumes
    • Tape Gateway → virtual tape library

12. Practice Questions

Question 1

A company needs to store millions of images and videos. The data must be highly durable and accessible by multiple applications. Which AWS service should the company use?

A. Amazon EBS
B. Amazon EFS
C. Amazon S3
D. Instance Store

Answer: C. Amazon S3

Explanation: Amazon S3 is object storage designed for highly scalable storage of files, images, videos, backups, and datasets.

Question 2

An application running on several Linux EC2 instances requires a shared file system that can be mounted by all instances. Which service should be used?

A. Amazon S3
B. Amazon EFS
C. Amazon EBS
D. Amazon S3 Glacier Deep Archive

Answer: B. Amazon EFS

Explanation: Amazon EFS provides an elastic, shared file system for Linux workloads and can be mounted by multiple instances.

Question 3

A company runs Windows applications that require a shared file system using SMB and integration with Microsoft Active Directory. Which service is most appropriate?

A. Amazon EFS
B. Amazon S3
C. Amazon FSx for Windows File Server
D. FSx for Lustre

Answer: C. Amazon FSx for Windows File Server

Explanation: FSx for Windows File Server provides managed Windows file shares using SMB and supports Active Directory integration.

Question 4

Which storage option is most appropriate for temporary scratch data that requires very low latency on an EC2 instance?

A. Amazon S3
B. Amazon EBS
C. Amazon EFS
D. EC2 Instance Store

Answer: D. EC2 Instance Store

Explanation: Instance Store is local to the EC2 host and provides very fast temporary storage. It is ephemeral and should not be used for persistent data.

Question 5

A company needs persistent block storage for an EC2 boot volume. The workload has typical performance requirements. Which EBS volume type should be selected?

A. Cold HDD
B. Throughput Optimized HDD
C. General Purpose SSD
D. Provisioned IOPS SSD only

Answer: C. General Purpose SSD

Explanation: General Purpose SSD is suitable for most workloads and can be used as an EC2 boot volume.

Question 6

A company must retain compliance archives for many years. The data is rarely accessed, and retrieval within 12 hours is acceptable. Which S3 storage class is generally the most cost-effective?

A. S3 Standard
B. S3 Standard-IA
C. S3 Glacier Instant Retrieval
D. S3 Glacier Deep Archive

Answer: D. S3 Glacier Deep Archive

Explanation: S3 Glacier Deep Archive is intended for long-term retention and is generally the lowest-cost S3 storage class when slow retrieval is acceptable.

Question 7

Which S3 feature helps recover an object after it has been accidentally overwritten?

A. S3 Versioning
B. S3 Lifecycle Management
C. S3 Transfer Acceleration
D. S3 Multipart Upload

Answer: A. S3 Versioning

Explanation: Versioning maintains previous versions of objects so that an earlier version can be restored.

Question 8

An organization wants on-premises applications to access file shares while the files are stored as objects in Amazon S3. Which AWS Storage Gateway configuration should be used?

A. Volume Gateway with Stored Volumes
B. Volume Gateway with Cached Volumes
C. File Gateway
D. Tape Gateway

Answer: C. File Gateway

Explanation: File Gateway provides SMB or NFS file shares and stores the files as objects in Amazon S3.

Question 9

An on-premises application requires iSCSI block storage. The company wants the primary copies of the data to remain on premises while storing backups in AWS. Which option meets these requirements?

A. File Gateway
B. Volume Gateway with Stored Volumes
C. Volume Gateway with Cached Volumes
D. Tape Gateway

Answer: B. Volume Gateway with Stored Volumes

Explanation: Stored Volumes keep the primary data on premises and store snapshots or backups in AWS.

Question 10

A company wants one service to automate and centrally manage backups across multiple AWS services. Which service should it use?

A. Amazon EBS
B. Amazon S3 Versioning
C. AWS Backup
D. AWS Storage Gateway

Answer: C. AWS Backup

Explanation: AWS Backup centralizes and automates backup policies, schedules, monitoring, and retention across supported AWS resources.