Design Data Storage Solutions – AZ-305 Study Guide
This domain accounts for 20–25% of the exam and asks you to recommend the right data store and protection strategy for relational, semi-structured, and unstructured data — balancing features, performance, cost, and durability. The exam gives requirements (schema, scale, latency, compliance, recovery objectives) and expects the best-fit recommendation. Know the Azure SQL family, Cosmos DB, Blob/Data Lake, and the redundancy and recovery options.
Relational Data
The Azure SQL family — pick by control vs compatibility:
| Option | When to recommend |
|---|---|
| Azure SQL Database (PaaS) | New cloud-native apps; minimal admin; don't need instance features |
| Azure SQL Managed Instance (PaaS) | Migrations needing SQL Agent, cross-database queries, CLR |
| SQL Server on Azure VM (IaaS) | Full OS/instance control; features PaaS lacks |
Compute tiers and scalability:
- Serverless tier auto-scales and auto-pauses — recommend for spiky/intermittent workloads.
- Read scale-out / read replicas offload reporting reads from the transactional primary.
- Elastic pools share resources across many databases with variable demand.
Open-source engines — Azure Database for PostgreSQL and MySQL (managed PaaS) when the app uses those.
Semi-Structured and Unstructured Data
| Store | Use for |
|---|---|
| Azure Cosmos DB | Semi-structured/JSON, global distribution, low-latency key access, elastic scale |
| Azure Blob Storage | Unstructured objects (media, backups, logs) at scale, with access tiers |
| Azure Data Lake Storage Gen2 | Big-data analytics files with hierarchical namespace and ACLs |
| Azure Files | SMB/NFS file shares for lift-and-shift |
Balancing features, performance, and cost: assign Blob access tiers (Hot / Cool / Archive) by access frequency with lifecycle management to transition data automatically.
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