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Difficulty: MediumData Redundancy and High Availability

A company is designing a high-availability storage solution in the Azure East US region. The solution will support a critical database application and has the following requirements:

1. The application's virtual machines run on Premium SSD managed disks. The disks must survive a zone failure within the primary region with zero data loss (RPO = 0).
2. The transaction logs are backed up to a standard General Purpose v2 storage account. These backups must survive a regional outage of the primary region.
3. The backup data must be readable in the secondary region at all times to allow a secondary reporting application to run audit reports without initiating a failover.

Which two storage configurations should you recommend to meet these requirements?

  1. Zone-redundant storage (ZRS) for the Premium SSD managed disksAnswer
  2. Read-access geo-redundant storage (RA-GRS) for the backup storage accountAnswer
  3. C
    Locally-redundant storage (LRS) for the Premium SSD managed disks
  4. D
    Geo-zone-redundant storage (GZRS) for the backup storage account

Answer

The correct configurations are Zone-redundant storage (ZRS) for the Premium SSD managed disks and Read-access geo-redundant storage (RA-GRS) for the backup storage account.
To satisfy the first requirement, the Premium SSD managed disks must use Zone-redundant storage (ZRS) because it replicates data across three availability zones in the primary region, ensuring the application survives a zone failure with zero data loss. To satisfy the second and third requirements, the backup storage account must use Read-access geo-redundant storage (RA-GRS) because it replicates the data to a secondary region for disaster recovery and provides a read-only endpoint in the secondary region that is available at all times without initiating a failover.

Step-by-Step Solution

1
Analyze the virtual machine disk storage requirements.
The Premium SSD managed disks must survive a zone failure with zero data loss (RPO = 0). Locally-redundant storage (LRS) does not provide zone resilience, so Zone-redundant storage (ZRS) is required.
ZRS replicates managed disk data synchronously across three availability zones within the primary region.
2
Analyze the backup storage account requirements.
The backup storage account must survive a regional outage and allow read access in the secondary region at all times without failover.
Geo-zone-redundant storage (GZRS) and Geo-redundant storage (GRS) do not expose read access to the secondary region unless a failover is triggered. Adding the Read-Access option (RA-GRS or RA-GZRS) is necessary to allow the reporting application to read backups in the secondary region before failover.

Key Concept

Azure storage redundancy tiers and their capabilities regarding availability zone failure resilience, regional disaster recovery, and read access to secondary replica regions.
Estimated Time:2m 0s
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Topics

Data Redundancy and High Availability

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