Storage services

AWS offers object storage (S3), block storage (EBS, instance store), file storage (EFS, FSx), hybrid storage (Storage Gateway), and central backup (AWS Backup). Know the S3 storage classes and lifecycle policies.

Object storage

• Amazon S3: Stores objects (files plus metadata) in buckets with virtually unlimited capacity and 11 nines of durability. Used for static websites, backups, data lakes, and media.

S3 storage classes

• S3 Standard: Frequently accessed data; lowest latency; data stored across at least three AZs.
• S3 Intelligent-Tiering: Automatically moves objects between access tiers when access patterns change or are unknown; small monitoring fee, no retrieval fees.
• S3 Standard-Infrequent Access (Standard-IA): Infrequently accessed data that still needs fast access; lower storage price plus a per-GB retrieval fee.
• S3 One Zone-IA: Like Standard-IA but stored in a single AZ: cheaper, for data you can re-create.
• S3 Express One Zone: Single-AZ, highest-performance class for latency-sensitive applications.
• S3 Glacier Instant Retrieval: Archive data accessed about once a quarter that needs millisecond retrieval.
• S3 Glacier Flexible Retrieval: Archives retrieved in minutes to hours.
• S3 Glacier Deep Archive: Lowest-cost storage for long-term retention; retrieval within 12 to 48 hours.

Lifecycle policies

• S3 Lifecycle rules automatically transition objects to cheaper classes as they age (for example, Standard to Standard-IA after 30 days, then to Glacier Deep Archive after a year) and can expire (delete) objects.
• Use them for logs, backups, and compliance archives with predictable aging.

Block storage

• Amazon EBS: Persistent block volumes for an EC2 instance in one AZ. Data survives instance stop and start; snapshots back up to S3.
• Instance store: Temporary block storage physically attached to the host. Very fast, but data is lost when the instance stops or terminates.

File storage

• Amazon EFS: Serverless, elastic NFS file system for Linux that many instances can share across AZs.
• Amazon FSx: Fully managed third-party file systems, such as FSx for Windows File Server (SMB), FSx for NetApp ONTAP, and FSx for OpenZFS.

Hybrid, backup, and recovery

• AWS Storage Gateway: Gives on-premises applications access to cloud storage with a local cache: S3 File Gateway, Volume Gateway, and Tape Gateway (virtual tape library).
• AWS Backup: Centrally manage and automate backups across services (EBS, RDS, DynamoDB, EFS, FSx, and more) with backup plans and retention policies.
• AWS Elastic Disaster Recovery: Continuously replicates servers to AWS so you can recover quickly after an outage.