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Question

Difficulty: MediumData Redundancy and High Availability

A logistics company is designing an Azure storage solution for a fleet tracking application. The application will store telemetry data as block blobs in a General Purpose v2 (GPv2) storage account. The solution must meet the following requirements:

* The storage must survive the failure of an entire availability zone in the primary region without data loss or downtime.
* The data must be replicated to a paired secondary region to protect against a regional disaster.

Which two redundancy options meet these requirements?

  1. Geo-zone-redundant storage (GZRS)Answer
  2. Read-access geo-zone-redundant storage (RA-GZRS)Answer
  3. C
    Geo-redundant storage (GRS)
  4. D
    Zone-redundant storage (ZRS)

Answer

Geo-zone-redundant storage (GZRS) and Read-access geo-zone-redundant storage (RA-GZRS)
The correct options are Geo-zone-redundant storage (GZRS) and Read-access geo-zone-redundant storage (RA-GZRS). GZRS replicates data across three availability zones in the primary region and also replicates it asynchronously to a secondary region, providing protection against both zone-level and region-level failures. RA-GZRS offers the same replication capabilities with the added benefit of read access to the secondary region, which also satisfies the core resiliency constraints.

Step-by-Step Solution

1
Analyze the primary region high availability requirement.
Survival of an availability zone failure requires synchronous replication across multiple availability zones in the primary region (ZRS or GZRS/RA-GZRS). Locally redundant options (LRS and GRS) are eliminated because they replicate within a single datacenter in the primary region.
GRS uses LRS in the primary region, meaning a zone outage containing that datacenter would cause data unavailability.
2
Analyze the disaster recovery requirement.
Protection against a regional disaster requires replication to a secondary region (GRS, RA-GRS, GZRS, or RA-GZRS). Local or zonal-only redundancy options (LRS and ZRS) are eliminated because they do not replicate outside the primary region.
ZRS only replicates within the primary region, meaning a regional outage would result in data loss or unavailability.
3
Combine the requirements to identify the matching redundancy options.
Only Geo-zone-redundant storage (GZRS) and Read-access geo-zone-redundant storage (RA-GZRS) provide both zone-level redundancy in the primary region and geo-replication to a secondary region.
Both GZRS and RA-GZRS satisfy the combined constraints of surviving a zone failure and providing regional disaster recovery.

Key Concept

Azure Storage redundancy options combine local, zonal, and regional replication strategies. Surviving a zone outage requires ZRS-based primary replication, while surviving a regional outage requires geo-replication.
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Topics

Data Redundancy and High Availability

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