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Difficulty: MediumDesign Compute High Availability

A retail company plans to migrate its inventory reconciliation service to Azure Virtual Machines. The service must achieve a cumulative virtual machine uptime SLA of 99.99% and must be resilient against the failure of an entire datacenter.

Which virtual machine deployment configuration should you design to satisfy these requirements?

  1. A
    Deploy the virtual machines inside a single Availability Zone using an Availability Set.
  2. Deploy the virtual machines across multiple Availability Zones in the same Azure region.Answer
  3. C
    Deploy the virtual machines as Azure Spot Virtual Machines across multiple Availability Zones.
  4. D
    Deploy the virtual machines in a single Availability Zone using a Virtual Machine Scale Set.

Answer

Deploy the virtual machines across multiple Availability Zones in the same Azure region.
Deploying virtual machines across multiple Availability Zones in the same Azure region guarantees a 99.99% uptime SLA for at least one instance. This architecture ensures that if a single datacenter or zone experiences an outage, instances in the remaining zones continue to operate, meeting both the high availability SLA and the zone-resilience requirement.

Step-by-Step Solution

1
Analyze the service's high availability SLA and resilience requirements.
The target SLA is 99.99% uptime for compute instances, and the architecture must survive a datacenter-level outage.
This establishes the minimum infrastructure boundaries required to design the compute deployment.
2
Evaluate the SLA guarantees of different Azure compute deployment models.
Single-zone Availability Sets provide 99.95% SLA. Multi-zone deployments (deploying VMs across two or more Availability Zones in a region) guarantee 99.99% SLA.
Matching the SLA requirements with Azure SLA documentation determines which architectural options are viable.
3
Assess the susceptibility of each configuration to datacenter failure.
Multi-zone placement distributes VMs across physically separate datacenters with independent power, cooling, and networking. Single-zone placements (including Availability Sets or single-zone Scale Sets) concentrate resources within a single zone.
This ensures the solution provides the necessary resilience to survive a localized datacenter disaster.

Key Concept

Azure Virtual Machine High Availability SLAs and Zonal Redundancy
Estimated Time:1m 30s
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Topics

Design Compute High Availability

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