# AWS S3 Cheat Sheet: Ace Your Solutions Architect Associate Exam! ## **S3 Basics** * **S3 (Simple Storage Service)** is an **object storage** service for storing any amount of data. * **Objects** (files) are stored in **Buckets** (containers). * **Global namespace**: Bucket names must be **globally unique**. * Data is **automatically replicated** across multiple Availability Zones (AZs). --- ## **Storage Classes** ![](https://cdn.hashnode.com/res/hashnode/image/upload/v1741563358728/9dd2c4dd-f15e-49e9-a37c-41b719d27e3d.webp align="center")

Storage Class

Use Case

Durability

Availability

S3 Standard

Frequently accessed data

99.999999999% (11 9s)

99.99%

S3 Intelligent-Tiering

Auto moves objects between tiers

99.999999999%

99.9%

S3 Standard-IA

Infrequent access, lower cost

99.999999999%

99.9%

S3 One Zone-IA

IA but stored in one AZ

99.999999999%

99.5%

S3 Glacier

Archival storage, retrieval time minutes to hours

99.999999999%

N/A

S3 Glacier Deep Archive

Cheapest, retrieval 12-48 hours

99.999999999%

N/A

--- ## **Security & Access Control** ### **Encryption**: * **SSE-S3** (Server-side, managed by S3) * **SSE-KMS** (AWS KMS keys) * **SSE-C** (Customer-managed keys) * **Client-side encryptio** ### **Access Control**: * **Bucket Policies** (JSON-based, IAM-style permissions) * **IAM Policies** (User/role-based permissions) * **ACLs (Access Control Lists)** (Legacy method, not recommended) * **Block Public Access** (Prevents accidental public exposure) ### **MFA Delete**: * Requires **Multi-Factor Authentication (MFA)** to delete objects. * Only works with **root user**.  --- ## **Data Management & Performance** ### **Versioning**: * Keeps multiple versions of an object. * Protects against accidental deletion. ### **Lifecycle Policies**: * Automates transitions between storage classes. * Example: Move to **Standard-IA** after 30 days, then **Glacier** after 90 days. ### **Replication**: * **Cross-Region Replication (CRR)**: Replicates objects **between AWS regions**. * **Same-Region Replication (SRR)**: Replicates objects **within the same region**. * Must **enable versioning** for replication. ### **Transfer Acceleration**: * Speeds up uploads using AWS **Edge Locations (CloudFront network)**. ### **Multipart Upload**: * Recommended for files **larger than 100MB**, required for **\>5GB**. --- ## **Event Notifications & Logging** ### **S3 Event Notifications** can trigger: * **SNS (Simple Notification Service)** * **SQS (Simple Queue Service)** * **Lambda (Serverless Processing)** ### **Logging & Auditing**: * **Server Access Logs** (S3 writes logs to another bucket) * **CloudTrail** (Tracks API calls and activities) --- ## **Cost Optimization** * **S3 Storage Pricing**: * Charged for **storage used, requests, data transfer**. * Use **Glacier for long-term storage**. * **Reduce costs using Lifecycle Policies** and **Intelligent-Tiering**. * **Use S3 Object Lock** instead of **Versioning** to protect data at a lower cost. ## **High Availability & Disaster Recovery** * **Data stored across multiple AZs** (except One Zone-IA). * **Cross-Region Replication (CRR)** for **multi-region DR**. * **Glacier & Object Lock** for data **immutability & compliance**. --- ## **S3 Exam Tips** ✔ **IAM Policies grant permissions to S3 buckets. IAM Users/Groups need explicit access** ✔ **Bucket Policies can allow public access, but "Block Public Access" must be disabled** ✔ **Versioning cannot be disabled once enabled (only suspended)** ✔ **Multipart Upload required for files > 5GB** ✔ **Glacier is the cheapest storage but takes time to retrieve** ✔ **Use S3 Transfer Acceleration for high-speed global uploads** ✔ **Cross-Region Replication requires Versioning to be enabled** ✔ **Use S3 Object Lock for Write-Once-Read-Many (WORM) scenarios** ✔ **CloudFront can cache and accelerate S3 content delivery** ## **Final Tip** If a question asks about **security & access control**, think **IAM Policies, Bucket Policies, ACLs, and Block Public Access**. If a question asks about **cost optimization**, think **Lifecycle Policies, Intelligent-Tiering, Glacier, and S3 One Zone-IA**.