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Difficulty: Very hardData Redundancy and High Availability

A multinational e-commerce company uses an Azure General Purpose v2 (GPv2) storage account to store product catalog images. The account is configured with Read-Access Geo-Zone-Redundant Storage (RA-GZRS). The primary region is East US (which supports availability zones) and the secondary paired region is West US (which does not support availability zones for standard GPv2 storage accounts).

The company's application is designed with a connection string that reads from the primary endpoint (catalog.blob.core.windows.net) and automatically falls back to the read-only secondary endpoint (catalog-secondary.blob.core.windows.net) if a primary read request fails.

A major disaster causes a complete outage of the East US region. The operations team initiates a customer-managed failover for the storage account. The last sync time reported prior to the outage was 8 minutes ago.

What is the state of the storage account and the application endpoints after the failover completes?

  1. The storage account redundancy is converted to Locally Redundant Storage (LRS) in West US. The primary endpoint resolves to West US, and the secondary endpoint is no longer accessible.Answer
  2. B
    The storage account redundancy is converted to Zone-Redundant Storage (ZRS) in West US. The primary endpoint resolves to West US, and the secondary endpoint is no longer accessible.
  3. C
    The storage account redundancy remains Read-Access Geo-Zone-Redundant Storage (RA-GZRS). The primary endpoint remains inactive, and the application must be updated to write directly to the secondary endpoint.
  4. D
    The storage account redundancy is converted to Geo-Redundant Storage (GRS) in West US, replicating back to East US. Both the primary and secondary endpoints remain active, with their roles reversed.

Answer

The storage account redundancy is converted to Locally Redundant Storage (LRS) in West US, the primary endpoint resolves to West US, and the secondary endpoint is no longer accessible.
When a customer-managed failover is initiated for an RA-GZRS storage account, the account is converted to a locally redundant tier in the secondary region. Because the target region (West US) does not support Availability Zones for standard storage accounts, the redundancy is converted to Locally Redundant Storage (LRS) rather than Zone-Redundant Storage (ZRS). Additionally, the DNS record for the primary endpoint is updated to resolve to the new primary region (West US), while the secondary endpoint is retired and becomes inaccessible since the account is no longer geo-replicated.

Step-by-Step Solution

1
Determine the impact of customer-managed failover on storage redundancy configuration.
The storage account loses its geo-redundant capability (GZRS/RA-GZRS) and is converted to a local redundancy tier in the secondary region.
Failover changes the primary location of the storage account to the secondary region, which strips the geo-replication configuration.
2
Evaluate availability zone support in the secondary region (West US) for standard GPv2 storage accounts.
West US does not support availability zones. Therefore, the account cannot be converted to Zone-Redundant Storage (ZRS).
If the secondary region does not support availability zones, a GZRS storage account is converted to LRS instead of ZRS during failover.
3
Analyze endpoint DNS behavior after the failover completes.
The primary endpoint (catalog.blob.core.windows.net) DNS record is updated to point to the West US region. The secondary endpoint (catalog-secondary.blob.core.windows.net) is removed.
The former secondary region becomes the new primary region, and because the account is no longer geo-replicated, the read-only secondary endpoint is disabled.

Key Concept

Azure Storage customer-managed failover mechanics and regional feature availability constraints.
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Topics

Data Redundancy and High Availability

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