Quick Note — Recommend a High Availability Solution for Semi-Structured and Unstructured Data
AZ-305 › Unit 3: Design business continuity solutions › Design for high availability › Recommend a high availability solution for semi-structured and unstructured data
Quick Note — Recommend a High Availability Solution for Semi-Structured and Unstructured Data
A media company streams videos and serves user-uploaded thumbnails from Azure Blob Storage accounts in three regions. One Friday evening their Singapore region experiences a 40-minute storage outage. Customer-visible impact: zero. Internal impact: an oncall engineer logs into Azure Monitor, sees the storage account has failed over to its paired region, and goes back to dinner. Six months earlier the architect had picked RA-GZRS over LRS to save the business roughly on storage replication cost — and the executives second-guessed the line item every quarter. The Friday-night non-event paid back the entire premium in a single outage.…
Retrieval target
- Recommend a High Availability Solution for Semi-Structured and Unstructured Data
- Closed-book recall
- 5 minutes
- Open the full lesson after a miss
Decision anchors
| Prompt | Compact answer |
|---|---|
Cosmos DB multi-region writes | An account-level setting (formerly 'multi-master') that lets clients write to any region the account is configured in. Each region becomes a primary; writes propagate to all other regions asynchronously. Brings write latency down to single-digit ms for globally distributed users. Trade-offs: per-region RU multiplier, weaker effective consistency, and conflict resolution required. |
| Cosmos DB automatic vs manual failover | An account property that controls behaviour when a region becomes unavailable. Automatic failover (single-region writes) — Cosmos detects the outage, picks the next priority region from your configured failover priority list, and re-routes writes. Transparent to clients using the global account endpoint. Manual failover — you call the API to swap primaries (typically for DR drills).… |
RA-GRS (Read-Access Geo-Redundant Storage) | GRS variant that exposes the secondary region's data as a read-only endpoint (different URL — <account>-secondary.blob.core.windows.net). Lets apps read from the secondary at any time, not just after failover. Caveat: the secondary lags primary by minutes due to async replication — reads are eventually consistent. Pick when DR-region reads matter or you want read-load offload for global readers. |
RA-GZRS (Read-Access Geo-Zone-Redundant) | The strongest Storage redundancy: ZRS in primary (sync across AZs) + 3 async copies in paired region + secondary endpoint for reads. Survives zone failure with zero RPO, region failure with minutes of RPO, and gives global read offload. Highest cost in the redundancy family. Use for mission-critical content where any failure mode is unacceptable. |
Read the answers once, then cover the right-hand column and reconstruct each one from the prompt. A useful answer names the requirement, the recommended control or service boundary, and the nearest alternative it rejects. If you can only recognize the answer after seeing it, retrieval is not yet secure.
Ninety-second explanation
Without notes, explain:
- What requirement signals this learning objective rather than a neighbouring one?
- Which two solution families are most likely to be compared?
- Which hard constraint eliminates the strongest distractor?
- What identity, network, data, or failure boundary must appear in the design?
- Which operational test would prove the recommendation works?
Then compare your explanation with the full lesson. Record the missing decision rule—not merely the missed product name—in your error log.
When to open the full lesson
Open the curriculum-linked lesson when you cannot explain a comparison, when a scenario depends on a numeric limit or SKU feature, or when the service is on a retirement path. Use current Microsoft Learn documentation for availability, limits, pricing, naming, and migration milestones; the quick note is intentionally compact.
Source and freshness
Derived from the linked AZ-305 lesson and retrieval deck, grounded in both attached course sources. Reviewed 2026-08-02. Current Microsoft documentation controls changing product contracts.