Storage services and storage classes

Foundational notes for AWS Certified Cloud Practitioner (CLF-C02). Read them in order the first time through, then use them as a revision sweep before you book.

11 study points. Everything here is exam-oriented: each point is a fact or a distinction that CLF-C02 items are built on. Test yourself against the practice exam once you can explain a section without re-reading it.

Storage

Amazon S3 (Simple Storage Service) is designed for an extraordinary level of durability: 99.999999999% (eleven nines). This means that if you store 10 million objects in S3, you can expect to lose a single object once every 10,000 years. S3 also offers 99.99% availability, meaning it is accessible almost all the time. These guarantees make S3 the go-to choice for storing anything from website images to critical business backups.

Amazon S3 Glacier is AWS’s low-cost archival storage service, perfect for data you need to keep but rarely access, such as compliance records or old log files. You can interact with Glacier by setting S3 lifecycle policies that automatically move older data into Glacier, or by using the Java and .NET SDKs, or by calling the RESTful API directly. Note that the AWS CLI does not support direct Glacier operations. Retrieval times range from minutes to hours depending on the retrieval tier you choose.

AWS CloudFormation lets you manage your entire infrastructure as code by writing template files in JSON or YAML. Instead of manually clicking through the AWS Console to create servers, databases, and networks, you describe all your resources in a template and CloudFormation provisions them for you. This approach is repeatable, version-controlled, and dramatically reduces the risk of human error. For example, you can spin up an identical copy of your production environment for testing with a single command.

S3 Bucket Policies are JSON-based access policies that apply to an entire bucket and all the objects within it. They are the right tool when you need to make an entire bucket publicly readable, such as when hosting a static website. For more granular control over individual objects, you would use Access Control Lists (ACLs) instead. Understanding when to use bucket policies versus ACLs is an important part of securing your S3 data.

Amazon S3 Transfer Acceleration enables fast, easy, and secure file transfers over long distances between your client and an S3 bucket. It works by routing your upload through the nearest AWS Edge Location, which then transfers the data to S3 over AWS’s optimized internal network. For example, if a user in Australia needs to upload a large file to a bucket in the US-East region, Transfer Acceleration can significantly reduce upload time. This is especially valuable for global applications where users are spread across continents.

S3 offers multiple storage classes to help you optimize costs based on how frequently you access your data. S3 Standard is for frequently accessed data, S3 Standard-IA (Infrequent Access) is cheaper but charges a retrieval fee, S3 One Zone-IA stores data in a single AZ for even lower cost, and S3 Glacier is for long-term archival. By using lifecycle policies, you can automatically transition objects between these classes as they age, saving money without any manual effort.

S3 Versioning is a feature that keeps multiple variants of an object in the same bucket. When enabled, every time you overwrite or delete a file, S3 preserves the previous version rather than destroying it. This protects you from accidental deletions and application bugs that might corrupt your data. For example, if someone accidentally deletes an important configuration file, you can simply restore the previous version in seconds.

Amazon Elastic File System (EFS) is a fully managed, scalable file storage service that can be mounted by multiple EC2 instances simultaneously. Unlike EBS, which attaches to a single instance, EFS acts like a shared network drive. This makes it ideal for workloads like content management systems or development environments where multiple servers need access to the same files. EFS automatically grows and shrinks as you add or remove files, so you never need to provision capacity in advance.

Amazon FSx provides fully managed third-party file systems. FSx for Windows File Server offers a native Windows file system built on Windows Server, complete with SMB protocol support and Active Directory integration. FSx for Lustre is a high-performance file system optimized for compute-intensive workloads like machine learning and video processing. These services let you use familiar file system tools without managing the underlying infrastructure.

AWS Storage Gateway is a hybrid storage service that connects your on-premises environment to AWS cloud storage. It provides three gateway types: File Gateway for storing files as objects in S3, Volume Gateway for block storage backed by S3 snapshots, and Tape Gateway for replacing physical tape backups with virtual tapes in S3 and Glacier. For example, a company migrating to the cloud can use Storage Gateway to keep local access to frequently used data while automatically backing everything up to AWS.

When choosing a storage solution on AWS, think about four factors: how frequently you access the data, how fast you need to retrieve it, how durable it needs to be, and how much you’re willing to pay. S3 is ideal for object storage like images and documents. EBS is best for block storage attached to a single EC2 instance, like a hard drive. EFS works when multiple instances need shared file access. Glacier is for archival. Matching the right service to your use case is key to both performance and cost efficiency.

Where to go next

Back to the AWS Cloud Practitioner overview.
Look up any service you could not name in the AWS services glossary.
Sit the 80-item practice exam once two or three note pages are solid.