Azure Availability Zones
Overview
Azure Availability Zones are designed to reduce a single point of failure given a specific IaaS scenario, mainly described as:
“fault-isolated locations within an Azure region, providing redundant power, cooling, and networking. Availability Zones allow customers to run mission-critical applications with higher availability and fault tolerance to datacenter failures.”.
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The Difference Between Availability Sets – Availability Zones – Region Pairs
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| Feature | Capability / Provide |
| Availability Sets | High-availability protection from hardware, network, and power failures in a DC |
| Availability Zones | High-availability protection against the loss of entire DC(s) |
| Region pairs | Disaster Recovery that protects from the loss of an entire region |
Top Features Of Azure Availability Zones:
- Availability Zones (AZ) are physically separated locations within a specific Azure region
- Each AZ has independent power, network, and cooling
- AZ locations are chosen based on a per-region risk assessment
- AZs are designed to reduce single points of failure in the platform
How Can Azure Availability Zones Help You?
Let's discuss 3 approaches where Availability Zones can help you increase resiliency:
- High-availability and Disaster Recovery
- Low Latency for synchronous replication
- Protection from data center-level failure
High-Availability and Disaster Recovery:
Native HA and DR support through Availability Zones and Regional pairs. Each AZ enabled region has a minimum of three zones. All regions have one region pair providing data replication with data residency.
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Low Latency for synchronous replication:
Zones are close enough to each other for synchronous replication, meaning high-availability for applications and minimal data loss.
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Protection from data center-level failure:
Each zone is physically separated with independent power, network, and cooling and logically separated through zone-isolated services.
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Example Of A Web App Utilizing Azure Availability Zones
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Considerations:
- Each zone consists of one or more data centers within a region
- You can load balance across all your VMs deployed in Availability Zones enabling scenarios with zonal frontends and cross-zone load balancing for the backend
- For regions that do not support Availability Zones, Availability Sets should still be leveraged for HA (and to get SLA).
- Availability Zones protect against local failures and covers a broader set. Planned maintenance just launched as a service and can be a substitute for update domains.
- Availability Sets and Availability Zones are not supported at the same time.
- In the case of Always On the SQL engineering team recommends you spread your nodes equally across the three zones for the highest availability
Documentation
Don´t forget to check out the Technical Documentation here!