What's changed: Deepened AZ-305 Chapter 2 (added comparison tables, scenarios, FAQs, exam traps, deep-dive paragraphs to each section; localized figures to Japanese)
2.2Designing Non-Relational and Storage
Understand non-relational and object storage—Azure Cosmos DB (APIs/consistency), Blob Storage (access tiers), Azure Files, and queues/tables. Pick stores matching access patterns.
For unstructured/key-value data, choose stores by access pattern: Cosmos DB for global low latency, Blob for objects.
2.2.1Non-relational choices
- Cosmos DB: globally distributed, single-digit-ms NoSQL; multiple APIs and five consistency levels.
- Blob Storage: objects/large data; optimize cost via access tiers (Hot/Cool/Cold/Archive).
- Azure Files: SMB/NFS shared files; useful for lift & shift.
- Queue/Table: Storage Queue = messaging, Table = structured key-value.
Common on AZ-305: global low-latency NoSQL = Cosmos DB (pick consistency by requirements), objects + tiered cost = Blob access tiers, shared files = Azure Files (SMB/NFS), archive = Blob Archive tier. Stronger Cosmos DB consistency increases latency/cost.
Cosmos DB consistency, strongest first: Strong → Bounded Staleness → Session → Consistent Prefix → Eventual. Session is the default and suits most apps.
AZ-305 non-relational design centers on "choosing the optimal store for the access pattern and consistency/geo/cost requirements." Cosmos DB provisions throughput in RU/s (provisioned/autoscale/serverless), and partition key selection is the key to scale and even distribution—pick a high-cardinality, low-skew key. Consistency levels are chosen by requirement, with latency/cost/availability trade-offs across the spectrum (Strong is strongest but adds latency/constraints; Session guarantees read-your-writes with good performance). Multi-region writes (multi-master) enable globally low-latency writes. Blob Storage auto-tiers via access tiers (Hot = frequent, Cool = infrequent with a minimum retention, Cold, Archive = cheapest but needs rehydration time to read) and lifecycle management, with redundancy designed via LRS/ZRS/GRS/GZRS. Azure Files (SMB/NFS) suits lift & shift; Azure NetApp Files suits high-performance needs. Queue/Table Storage are lightweight messaging/key-value; for richer features consider Service Bus / Cosmos DB. The key is to match read/write distribution, latency, geo-distribution, consistency, and cost (storage/retrieval/RU) to choose the right store and tier without over- or under-provisioning.
| Blob access tier | Use | Trait |
|---|---|---|
| Hot | Frequently accessed | High storage, low access cost |
| Cool | Infrequent (30+ days) | Lower storage; minimum retention |
| Cold | Rare (90+ days) | Even cheaper; still online |
| Archive | Long-term, near-never accessed | Cheapest; rehydration needed to read |
Scenario: Analyze log data frequently for the first 30 days, rarely after, but retain 7 years for compliance—minimize cost. → Use Blob lifecycle management rules to auto-move to Cool at 30 days and Archive at 90 days. Archive is cheapest but factor in rehydration time to read. Choose redundancy like GRS (geo-redundant) per requirements.
FAQ: Which Cosmos DB consistency? The default Session (read-your-writes) is optimal and well-balanced for most apps. For data that must be always latest (e.g., financial balances), Strong (more latency/cost). If availability and throughput are paramount and slightly stale reads are acceptable, Eventual. Choose by "how stale data you can tolerate."
Exam trap: Putting "infrequently accessed but must-be-instantly-available" data in the Archive tier is wrong—Archive is cheapest but unreadable until rehydration (hours). For rare-but-instant access, use Cool/Cold. Also, a skewed Cosmos DB partition key causes a hot partition that caps throughput.
2.2.2Section summary
- NoSQL = Cosmos DB (5 consistency levels) / objects = Blob (access tiers)
- Shared files = Azure Files / queue = Storage Queue
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Quick check
(just a quick review)Q1. You need a globally distributed NoSQL with single-digit-ms latency for worldwide users. What?
Q2. Store large, rarely accessed backups long-term at the lowest cost. Which Blob option?
Q3. Migrate an on-prem file server to a managed Azure share keeping the SMB protocol. What?
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