AWS has a lot of data services, and the names alone don’t tell you what each one is for. This post is a mental map — how the database, analytics, and data-movement services fit together, and how to pick between them. The mental map ┌─────────────────────────────────────────────────────────────┐ │ DATABASES (operational, low latency) │ ├─────────────────────────────────────────────────────────────┤ │ RDS relational SQL │ │ DynamoDB NoSQL key-value, serverless │ │ ElastiCache in-memory cache (Redis/Memcached) │ │ DocumentDB MongoDB-compatible document DB │ │ Neptune graph DB (nodes + edges) │ │ Timestream time-series DB │ │ Managed Blockchain Hyperledger/Ethereum │ ├─────────────────────────────────────────────────────────────┤ │ ANALYTICS (batch, big data, querying) │ ├─────────────────────────────────────────────────────────────┤ │ Redshift data warehouse (columnar SQL at scale) │ │ EMR managed Hadoop/Spark cluster │ │ Athena SQL queries directly on S3 │ │ QuickSight BI dashboards/visualization │ ├─────────────────────────────────────────────────────────────┤ │ DATA MOVEMENT │ ├─────────────────────────────────────────────────────────────┤ │ Glue managed ETL (extract/transform/load) │ │ DMS Database Migration Service │ └─────────────────────────────────────────────────────────────┘ Databases These are operational, low-latency stores — the databases an application reads and writes in real time....

RDS is a managed SQL database. AWS runs the database server — patching, backups, failover — and you just use it. It is where the structured data of an application lives. What RDS is A managed relational database: you pick an engine, and AWS does the operations. Supported engines: MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and Aurora — AWS’s own MySQL/Postgres-compatible engine. You connect with standard SQL drivers (JDBC/ODBC) over a hostname and port....

S3 is object storage — durable, effectively infinite, and accessed over an HTTP API. It is the default place to put blobs in AWS: images, backups, logs, static assets, anything. The core pieces Piece What it is Bucket The top-level container for objects. Its name is globally unique, and it lives in one region. Object A blob plus metadata, addressed by a key. The thing you actually store. Key The object’s “path” — e....

A single EC2 instance is a single point of failure. To make an app highly available and elastic — able to handle variable load and survive failures automatically — AWS gives you two services that work hand in hand: ELB and ASG. The two pieces Service What it does Question it answers ELB Distributes incoming traffic across multiple EC2s “How do users reach my fleet?” ASG Adds, removes, and replaces EC2s based on demand or health “How big should my fleet be?...

Once an EC2 instance is running, it needs somewhere to put data. AWS gives you three kinds of disk to attach to a VM, and each one behaves very differently. The options Type Storage Lifecycle Scope EBS Block, network-attached Persistent One AZ Instance Store Block, physically on the host Ephemeral — lost on stop/terminate One host EFS File (NFS), network share Persistent Multi-AZ Mental model EC2 ──attaches──> EBS volume (its own dedicated disk, persistent) EC2 ──has──────> Instance Store (host's physical NVMe, ephemeral) EC2 ──mounts───> EFS (network file share, many EC2s share it) In plain terms:...