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Difficulty: MediumDesign Storage and Non-Relational Data HA and DR

NovaHealth Solutions is designing a disaster recovery strategy for its clinical intake application. The application writes transactional check-in records to an Azure Storage account. You need to recommend a storage replication and recovery strategy that meets the following requirements:

* During a primary region outage, existing records must be readable within 15 minutes.
* During a primary region outage, write capabilities for new records must be restored within 1 hour.
* Data loss (RPO) for both reads and writes must be less than 15 minutes.
* Costs must be minimized.

Which storage configuration and disaster recovery strategy should you recommend?

  1. Configure the storage account to use Read-Access Geo-Redundant Storage (RA-GRS). During a primary region outage, point the application to the secondary read-only endpoint, and initiate a customer-managed failover to make the secondary region the new primary for write operations.Answer
  2. B
    Configure the storage account to use Geo-Redundant Storage (GRS). During a primary region outage, immediately initiate a customer-managed failover to make the secondary region the new primary for both read and write operations.
  3. C
    Configure the storage account to use Read-Access Geo-Redundant Storage (RA-GRS). During a primary region outage, immediately redirect all read and write requests to the secondary endpoint without initiating a failover.
  4. D
    Configure the storage account to use Geo-Redundant Storage (GRS). During a primary region outage, configure the application to write to the secondary endpoint while waiting for Microsoft to initiate a failover.

Answer

Configure the storage account to use Read-Access Geo-Redundant Storage (RA-GRS). During a primary region outage, point the application to the secondary read-only endpoint, and initiate a customer-managed failover to make the secondary region the new primary for write operations.
The correct strategy is to use Read-Access Geo-Redundant Storage (RA-GRS) and point the application to the secondary read-only endpoint during an outage to meet the 15-minute read RTO, while initiating a customer-managed failover to restore write capabilities within 1 hour. This ensures zero read downtime and restores write capabilities within the RTO while minimizing storage costs.

Step-by-Step Solution

1
Analyze read availability requirements during a primary outage.
Since existing records must be readable within 15 minutes, Geo-Redundant Storage (GRS) is insufficient because its secondary endpoint is not readable until a failover is completed (which can take up to 1 hour). Read-Access Geo-Redundant Storage (RA-GRS) must be used to provide immediate read access to the secondary region.
RA-GRS provides a secondary read-only endpoint that allows read access even when the primary region is unavailable, satisfying the 15-minute read RTO.
2
Analyze write recovery requirements during a primary outage.
Write capabilities must be restored within 1 hour. A customer-managed failover can be initiated on the RA-GRS storage account, which converts the secondary region into the new primary (with LRS) and restores write capabilities within the 1-hour window.
Before failover, the secondary endpoint of an RA-GRS account is strictly read-only. Initiating the failover changes the storage account type to LRS in the secondary region and opens it for writes.
3
Evaluate cost efficiency constraints.
RA-GRS meets all requirements. Read-Access Geo-Zone-Redundant Storage (RA-GZRS) would also meet the availability requirements but at a higher cost, and there are no requirements for zone-redundancy in the primary region.
To minimize costs, RA-GRS is preferred over RA-GZRS because it does not require zone-redundant storage in the primary region.

Key Concept

Read-Access Geo-Redundant Storage (RA-GRS) replication and customer-managed failover behavior.
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Topics

Design Storage and Non-Relational Data HA and DR

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